Baseball is commonly dubbed as "America's pastime," but to which people? We're not going to lie, we've heard plenty of sports fans—especially millennials—say something along the lines of "Baseball is boring!" That being said, baseball may not be in your top five list of favorite sports, but baseball cards can make for an amazing hobby that'll keep you busy in your free times. Plus you can financially benefit from your cards, as some of them have increased in value in recent years. But, of course, there are some cards that have unfortunately decreased in value over the years. So it's safe to say the old-school quote, "There are two sides to every issue" also applies to the process of collecting such cards.

We're not here to discourage you from collecting baseball cards. Please feel free to start a new collection if you haven't already done so. We're just trying to give you a heads up on which cards are of decent value and which cards have significantly dropped in value. Collecting such cards can turn out to be a multi-million dollar investment in the future, but you must have the non-education smarts to make these cards into remarkable valuable assets for card collectors in America and perhaps other countries such as Canada, Europe and Mexico. Unlike traditional stocks, these cards can last for years to come and their values will never show up as goose eggs.

Let's take a closer look at 20 baseball cards now worth a fortune and 10 that have plummeted in value.

30 Fortune: Frank Thomas 1990 Topps No-Name

Frank Thomas, also known as "The Big Hurt," is one of those MLB players you should know about. Thomas is a multi-talented hitter and one of the greatest players of the 1990s. And, let's fast forward to 2007, when Thomas became the 21st member of the 500 Home Run Club.

Thomas' powerful swing was the main reason why he was drafted seventh overall by the Chicago White Sox in the 1989 MLB Draft.

Thomas' 1990 Topps No-Name card is worth $50,000 in GEM-MT 10 condition today.

29 Fortune: Michael Jordan 1991 #SP1 Upper Deck

Michael Jordan, also known by his initials "MJ," was better known as being a prestigious Chicago Bulls star in the 1980s and 1990s, but many will forget that Jordan played minor league baseball for the Chicago White Sox organization in the mid 1990s. Jordan made that decision to honor his late father James R. Jordan Sr.

Despite the fact Jordan never became a big baseball star, Jordan's 1991 #SP1 Upper Deck card is worth $2,000 in BGS 10 Pristine condition today.

28 Plummeted: Darryl Strawberry 1984 #182 Topps Rookie Card

Darryl Strawberry is known for his 17-year MLB career, particularly his first seven years with the New York Mets from 1983-1990. Strawberry was a member of the better Mets teams from 1984-1990, but that doesn't automatically mean that Strawberry's Mets cards were always expensive cards for collectors across the country.

In fact, Strawberry's 1984 #182 Topps Rookie Card is worth just $40 in GEM-MT 10 condition today. That's likely going to be a steal for you unless if you're flat out broke without a place to stay.

27 Fortune: Nolan Ryan 1993 #211 Pacific

Nolan Ryan, also known as "The Ryan Express," is a former MLB pitcher who pitched for the New York Mets, California Angels, Houston Astros and Texas Rangers. Ryan is also the all-time leader in no-hitters with seven (and three more than any other pitcher).

Despite the fact Ryan pitched seven no-hitters in his career, Ryan was never the winning pitcher of a perfect game nor ever won the Cy Young for his efforts on the mound.

Still, Ryan's 1991 #211 Pacific card is worth $1,150 plus $20 shipping and handling in PSA 9 condition today.

26 Fortune: Derek Jeter 1993 #279 Upper Deck Short Print

Even if you're not a New York Yankees fan, you're probably well-aware that Derek Jeter was a high-caliber shortstop who won five World Series—all with the Yanks, too.

Jeter was drafted straight out of Kalamazoo Central High School in 1992 and was exclusively evaluated by Houston Astros scout Hal Newhouser just days before the 1992 MLB Draft. Jeter was then drafted sixth overall by the Yanks.

Jeter's 1993 #279 Upper Deck Short Print card is worth up to $10,400 in GEM-MT 10 condition today.

25 Plummeted: Jose Canseco 1987 #620 Topps Rookie Card

Jose Canseco is a former MLB outfielder and designated hitter who established himself as one of the greatest power-hitters to ever grace a baseball diamond. Canseco was best known for his two stints with the Oakland Athletics in 1985-1992 and 1997.

That being said, Canseco's legacy was tainted in many media members and fans' minds. Just like the Hall of Fame vote, that affects card values and later caused the value of his 1987 #620 Topps Rookie Card to drop to $32.99 in PSA 9 condition.

24 Fortune: Alex Rodriguez 1994 #24 Electric Diamond Upper Deck Short Print

Alex Rodriguez, also known as "A-Rod," is a former MLB shortstop and third baseman who played 22 seasons in the league. While Rodriguez was best known as a New York Yankees star, Rodriguez actually began his career with the Seattle Mariners, who selected Rodriguez with the first overall pick of the 1993 MLB Draft even though he was only 17 at the time.

Rodriguez played for the M's from 1994-2000.

Despite the fact it's likely a forgotten fact Rodriguez was a Seattle Mariner, Rodriguez's 1994 #24 Electric Diamond Upper Deck Short Print card is still worth up to $600 in BGS 9.5 condition right now.

23 Fortune: Mike Trout 2011 Topps Update #US175 Rookie Card

Mike Trout, whose nickname is "The Millville Meteor," is a Los Angeles Angels center fielder who has achieved so much in his 27-year life so far. Trout is a seven-time MLB All-Star who won the AL MVP award in 2014 and 2016, respectively.

But Trout's 2011 Topps Update #US175 Rookie Card isn't worth much nowadays. In fact, Trout's rookie card is worth a rather reasonable $964 in GEM-MT 10 condition at the moment. As time goes on though, the value of this card will continue to increase as Trout remains the best player in baseball.

22 Plummeted: Roger Clemens 1984 Fleer

Roger Clemens is obviously a divisive figure now with the controversies that unfolded throughout and after his career ended, but in spite of all that, his 1984 Fleer card still has a pretty strong value of $550 in mint condition. Still, for a legend like Clemens, that feels pretty low. If somehow Clemens is voted into the Hall of Fame at this point, the value of this card would obviously go through the roof, so if this card's in your possession, it might be worth hanging on to for a few more years.

21 Fortune: Cal Ripken Jr. 1982 #21 Baltimore Orioles Future Stars Topps

Cal Ripken Jr., whose nickname is "The Iron Man," is a former MLB shortstop and third baseman who played his entire 21-season career with the Baltimore Orioles. The O's star is the son of the late Cal Ripken Sr., who played and coached with the O's.

The O's recently hit the 100-loss mark for the first time since 1988, but Ripken Jr. is a happier memory of the franchise.

Ripken Jr. won the 1983 World Series and was a 19-time MLB All-Star.

Ripken Jr.'s 1982 #21 Baltimore Orioles Future Stars Topps card is worth up to $1,225 in PSA 10 condition today.

20 Fortune: Rickey Henderson 1980 #482 Topps

Rickey Henderson, also known as "Man of Steal," is a former MLB left fielder who played for nine different teams from 1979-2003. Four of those nine stints were with the Oakland Athletics from 1979-1984, 1989-1993, 1994-95 and 1998.

Henderson is often regarded as the MLB's greatest lead-off hitter and base-runner. Moreover, Henderson was ranked in the league's top 100 all-time home run hitters at the end of his last Major League game in 2003.

If found in GEM-MT 10 condition, Henderson's 1980 #482 Topps card will be worth $27,500 right now.

19 Plummeted: Jerry Koosman/Nolan Ryan 1968 Topps #177 Rookie Card

Former pitchers Jerry Koosman and Nolan Ryan were two of the MLB's biggest rookies in the late 1960s, but that doesn't mean their joint rookie card always stayed at the same high-priced rate.

Yes, the Jerry Koosman/Nolan Ryan 1968 Topps #177 Rookie Card is the only recognizable rookie card of the MLB's strikeout king Nolan Ryan, but unless if you have a copy that's in MT 9 condition, it's most likely going to be worth a lowly amount under $1,000.

18 Fortune: Joe DiMaggio 1938 #274 Goudey Gum Company

Joe DiMaggio, whose nicknames were "Joltin' Joe" and "The Yankee Clipper," was a MLB center fielder who played his entire 13-year career with the New York Yankees.

DiMaggio's record 56-game hitting streak still stands to this day.

DiMaggio was inducted into the National Baseball Hall of Fame in 1955. DiMaggio's late brothers Vince (1912-1986) and Dom (1917-2009) were also MLB center fielders. So it's safe to say baseball ran in the DiMaggio family.

Anyhow, DiMaggio's #274 Goudey Gum Company card most recently sold for $288,000 in PSA Mint 9 condition in 2017.

17 Fortune: Joe Doyle 1909-1911 T206 (N.Y. Nat'l, Hands Up)

Joe Doyle is far from one of the most recognizable faces in the MLB. But, we have to inform you that Doyle's 1909-1911 T206 (N.Y. Nat'l, Hands Up) card is one of the most valuable cards among baseball card collectors.

Doyle pitched in the MLB for five seasons and posted a 22-21 record and a 2.21 ERA. When the card was introduced, Doyle was pitching for the New York Highlanders of the American League. Larry Doyle played for the New York Giants of the National League. That typo was corrected. Still, there were a handful of uncorrected cards, and they're worth $550,000 in VG 3 condition.

16 Plummeted: Sammy Sosa, 1990 Leaf

Given all the controversies surrounding Sammy Sosa in recent years and his recent denial/non-denial of what he used to hit so many home runs, it's unsurprising that the value of his rookie card is far lower than what it probably should be. Sosa's another example of how a tarnished legacy can affect one's value in the baseball card industry. Leaf cards from the '90s of stars tend to be worth a fortune, but this one of Sosa is worth only $20.

If attitudes about Sosa's legacy ever change, this one could go for a lot of money in the future.

15 Fortune: Eddie Plank 1909-1911 T206

Eddie Plank, whose nickname is "Gettysburg Eddie," was a MLB pitcher who pitched the majority of his career for the Philadelphia Athletics from 1901-1914. Plank was the first left-handed pitcher to win 200 games and then 300 games.

Plank currently ranks third place in all-time wins among LHPs with 326 career wins (11th all-time) and first in all-time career shutouts among LHPs with 66.

Plank's 1909-1911 T206 card is the second most desirable card in the T206 set of cards. This card is almost as tough as the Honus Wagner card from the same set. It's worth $675,000 in NM-MT 8 condition.

14 Fortune: Ty Cobb 1909-1911 T206

Ty Cobb, whose nickname was "The Georgia Peach," was a MLB outfielder who pitched the majority of his career with the Detroit Tigers from 1905-1926. Cobb was often credited for setting 90 MLB records. Cobb also ranked fifth all-time in games played and additionally committed 271 errors for the most by any American League OF.

However, Cobb's legacy was sort of tarnished by some of his antics both on and off the field. Still, that didn't drag down the value of the Ty Cobb 1909-1911 T206 card, which is worth $42,500 in NM-MT 8 condition.

13 Plummeted: Barry Bonds 1986 #11T Topps Rookie Card

Barry Bonds may not be deserving of a spot in the National Baseball Hall of Fame, but that's debatable. Bonds' 1986 #11T Topps Rookie Card isn't debatable.

Yeah, Bonds played 22 seasons in the MLB as a left fielder. Bonds also drew negative attention as a pivotal figure in the MLB's Mitchell Report scandal, and while you can debate his MLB hitting records, you can't debate the fact his Pittsburgh Pirates rookie card significantly dropped in value. It's as low as $23 right now.

12 Now Worth A Fortune: Roberto Clemente 1955 Topps #164

Roberto Clemente was a MLB outfielder who played his entire 18-season career with the Pittsburgh Pirates from 1955-1972. Clemente was best known for being the first Latino and Caribbean player to be enshrined in the National Baseball Hall of Fame in 1973.

Clemente was a 12-time MLB All-Star who played in 15 MLB All-Star Games. Clemente was also a two-time World Champion in 1960 and 1971.

Clemente was one of the greatest outfielders and hitters of his generation. Clemente's 1955 Topps #164 is the only recognizable rookie card with his face on it. It's worth $325,000 in MT 9 condition.

11 Fortune: Babe Ruth 1914 Baltimore News

Babe Ruth, whose nicknames were "The Bambino" and "The Sultan of Swat," was undoubtedly a New York Yankees star who surprisingly made his MLB debut with the rival Boston Red Sox. Ruth established a ton of hitting (and some pitching) records and was eventually inducted into the National Baseball Hall of Fame as one of the "First Five" inaugural members.

Ruth, however, succumbed to esophageal cancer at the age of 53 in 1948. Ruth was best known for his hitting abilities, which was the main reason why scouts were so intrigued by him, and this also drove up the value of his 1914 Baltimore News card to $925,000 in VG-EX 4 condition.