Yes, it's sometimes astonishing to hear the earnings of professional athletes. After all, they get paid big bucks just to play a game on TV.

Moreover, it boggles the mind to hear what athletes in certain sports pull in each year given the amount of perceived effort they exert competing in their chosen profession. For example, more than 200 PGA golfers broke the $100,000 mark in 2014 - just for chasing a little white ball around. Even baseball, America's pastime, doesn't seem to warrant some of the exorbitant eight (and nine) figure contracts of many of its players.

On the other hand, it seems more logical why athletes in other sports - say, rugby or football - make substantial stacks of cash. After all, they put their bodies and heads on the line on a daily basis, right? The ultimate extension of this logic is the fat payouts in the world of professional boxing. Sure, the bouts themselves aren't very long, but given that you're stuck in a ring with an opponent who is trying to beat the crap out of you, they seem pretty justifiable.

Lots of boxers have earned oodles of cash over the years. Some have done a poor job of hanging on to those winnings (Mike Tyson) while others have leveraged their relatively scant winnings into even fatter bank accounts (like boxer-turned-developer Tom Moyer, who passed away in November). But now that we're into 2015, here are the 15 richest former and current pro boxers by net worth:

15 T14. Wladimir Klitschko - $30 Million

One half of the only sibling pair on this list, Klitschko has not lost a fight in over a decade. The Ukranian "Steel Hammer" burst onto the scene by winning the gold medal in the Super Heavyweight division at the 1996 Olympics in Atlanta. Since then, Klitschko has amassed an amazing 63 victories, with all but ten coming by knockout. He and his wife (actress Hayden Panettierre of Nashville) welcomed their first child late last year. In April, Klitschko will defend his Heavyweight titles in April against undefeated American Bryant Jennings.

14 T14. Anthony Mundine - $30 million

North Americans may not have heard about this Australian fighter, but he's a household name down under. The former rugby player-turned-pugilist is a Muslim of Aboriginal descent, and he has compiled an impressive lifetime record of 47-6 with 27 knockouts. After getting clobbered by Joshua Clottey of Ghana in April, he bounced back in November to defeat Belorussian Sergey Rabchenko in November.

13 13. Shane Mosley - $35 million

"Sugar" won Fighter of the Year honors in both 1998 and 2000, and appeared destined to be one of the greatest fighters of all time after winning each of his 36 fights during his first eight years of pro boxing. But then Mosley lost back-to-back fights in 2002 to Vernon Forrest and would post a mediocre 9-9-1 record to finish out his career. The "straight-outta" Lynwood, California native earned title belts in the Welterweight and Lightweight, and Light Middleweight classes during his career before retiring after his 2013 thrashing at the hands of the aforementioned Anthony Mundine.

12 T11. Bernard Hopkins - $40 million

"The Executioner" has compiled an impressive 55-7-2 record (with two no-contest bouts) over his 26-year career in which he fought in the Middleweight, Super Middleweight, and Light Heavyweight divisions. In one stretch from 1994 to 2005, he successfully defended his undisputed Middleweight crown twenty times before losing to Jermain Taylor in July of '05. The Philadelphia-born Hopkins is currently without a title belt after his loss in November to Sergey Kovalev by unanimous decision, even though he was the first fighter to take the Russian past eight rounds.

11 T11. Ricky Hatton - $40 million

The British born Hatton earned a total of $65 million in prize money during his 15-year career in the Light Welterweight and Welterweight classes. through his first decade of professional boxing, Hatton was undefeated in 43 bouts and held three Light Welterweight championship belts. Then he met up with Floyd Mayweather, Jr. in Las Vegas in 2007 and lost by TKO after ten rounds. Hatton would actually lose three of his final five fights before retiring in 2012.

10 10. Marvelous Marvin Hagler - $45 million

The adjective is listed above because he legally changed his name to "Marvelous" in 1982 because he was reportedly annoyed that boxing announcers weren't using it. The powerful-punching career middleweight did not lose a fight from 1976 until 1987 (though he did draw with Italy's Vito Antuofermo in 1979). The Newark, New Jersey native was the undisputed Middleweight Champion for 6 1/2 years, the second-longest streak in that weight class in the 20th century behind only Tony Zale from the 1940s. Hagler lost his title in 1987 to a top-five entrant on this list, then retired with a 62-3-2 record.

9 9. Vitali Klitschko - $65 million

The current mayor of Kiev, Ukraine, Vitali is five years old than his brother and also boasts a PhD in sports science. Klitschko retired in 2012 with an amazing record of 45-2 with 41 knockouts. His pro career began in 1996 after he switched from kickboxing, and he won his first Heavyweight title two years later. After a loss to another member of the richest boxer club, Klitschko regained his heavyweight belt in 2004 and held onto it until his retirement.

8 8. Muhammad Ali - $80 million

"The Greatest" hasn't been in the ring since 1981, but he continues to make an impact on the world just like he did when he was boxing. He won Olympic gold in 1960 in Rome and became the undefeated, undisputed heavyweight champ before being stripped of his titles for refusing to be drafted into the Vietnam War. He would regain that honor later in his career, which ended with an impressive 56 victories against just five defeats. Despite his Parkinson's disease diagnosis over three decades ago, Ali still continues to inspire people - even appearing in a 2015 Super Bowl ad for Toyota.

7 7. Manny Pacquiao - $110 million

Like Vitali, Pacquiao is a politician as well, having been elected to the Philippines' House of Representatives in 2010 and re-elected three years later. But "Pac-Man" is better known as the only fighter in history to win a world title in eight different weight classes. He is still defending his WBO Welterweight title with his 57 wins against just five losses and two draws. Pacquiao has been pulling down eight-figure paydays in every fight since 2008, and boxing fans around the world are still hoping that he steps into the ring with the top entrant on this list sometime soon. His last fight was a unanimous decision over American Chris Algieri in 2014.

6 6. Naseem Hamed - $105 million

The British-Yemeni fighter won all but his second-to-last fight in his career before retiring in 2002 at age 28. The southpaw earned 31 of his 36 wins by knockout, and he won his first world title at the age of 20. Hamed would go on to capture belts in the Featherweight, Bantamweight, and Super Bantamweight classes. Nicknamed "Prince," the flamboyant Hamed was known for his antics both entering and inside the ring. He's reported to have a portfolio worth nearly $105 million and once purchased everything on an entire street to keep his family close.

5 5. Sugar Ray Leonard - $120 million

Sugar Ray Leonard burst onto the world scene in 1976 by winning the gold medal at the 1976 Montreal Olympics in the Light Welterweight division. He turned pro early the following year and proceeded to tally 27 straight victories over the next 37 months (those were the days!) before losing to Roberto Duran in June of 1980. But the North Carolina native avenged the Duran loss five months later, and then earned title belts in three other weight classes (including his first Middleweight championship over the aforementioned Hagler in 1987). He retired for good in 1997 after getting only one victory in his final four career matches.

4 4. Lennox Lewis - $140 million

The last great heavyweight of the Western world, "The Lion" can boast defeats of boxing legends Mike Tyson, Evander Holyfield, and the younger Klitschko brother over a period of 3 1/2 years before hanging up his gloves in 2003. Like others on this list, the British-born Lewis won gold at the 1988 Olympics in Seoul in the Super Heavyweight division while fighting for Canada (where his family moved when Lennox was 12).  The most recent undisputed Heavyweight champion compiled a career record of 41 wins, two losses and a draw.

3 3. Oscar de la Hoya - $175 million

The greatest Mexican-American fighter in history earned his iconic status by winning an amazing 234 amateur fights and a 1992 Lightweight boxing gold medal for the U.S. at the Barcelona Olympics. En route to his 39-6 career pro record, the "Golden Boy" defeated an astonishing 17 world champions while winning ten world titles in half a dozen weight classes. After falling to the aforementioned Pacquiao in December of 2008, de la Hoya retired; but one big reason he remains so high on this list is that he's been on the promotion side of boxing for the past six years.

2 2. George Foreman - $250 million

Speaking of business acumen, the undisputed post-boxing career moneymaking champion is big George, who only had a net worth of around $5 million in the 1980s after his first retirement. But thanks to his supremely-popular line of miniature grills, Foreman was able to amass what today is a quarter billion-dollar fortune. After the Marshall, Texas native captured gold in the Heavyweight division at the 1968 Mexico City Olympics, Foreman won two world Heavyweight titles (one pre- and one post-retirement) over a career that spanned four decades. He retired in 1997 with an 76-5 record.

1 1. Floyd Mayweather, Jr. - $280 million

In contrast, Mayweather has made all of his dough inside the ring (he has no endorsement deals), where his prize money has totaled a whopping $405 million. "Money" is undefeated in 47 professional fights and is the current WBA, WBC, and The Ring Welterweight and Super Welterweight champion. He's supposed to announce his opponent for an upcoming May bout very soon; and the top contenders are Amir Khan or Miguel Cotto (or perhaps Pacquiao) for the Middleweight bout. His top challenger in the Super Welterweight class is Mundine, but there's no scheduled date for that meeting. One thing's for sure - whenever Mayweather fights, he gets paid - a minimum of $25 million for each of his last ten matches.