Athletes like Michael Jordan, John Elway, George Foreman and Magic Johnson earned fantastic amounts of money during their careers. But it was after they called it quits that the real money started rolling in.
So who from our current crop of athletes will be the next grill master? The next team owner? The next media mogul?
Click on to see the insanely rich who are destined to become insanely richer.
Milwaukee Bucks power forward Drew Gooden is already looking to life beyond the NBA.
In 2012 he signed a deal to open four Wingstop restaurants in the Orlando area.
David Vernon, the company's vice president of franchise sales, told Entrepreneur magazine that Gooden made a very smart move by taking on a partner who has casual-dining business know-how.
But at 32, one has to wonder how many years of fighting he has left in him. And because MMA is not as mainstream as boxing or many team sports, it seems the endorsement deals may dry up once the bouts end.
But St. Pierre is slowly reinventing himself as an actor. Sportsnet reports that he landed a role in the sequel to the hit film Captain America: The First Avenger, which is due out in spring 2014.
Three things are certain in life:
1. You will die.
2. You will pay taxes.
3. Americans always eat lots of burgers.
Mickelson has applied truism No. 3 to his financial portfolio.
According to Forbes magazine, he has invested in America's fastest-growing restaurant chain, Five Guys Burgers.
With the name, the personality and the speed, Bolt has already branded himself.
His app Bolt!, a simple action game "in which the athlete fights off pirates to claim his gold, with the occasional Gatorade energy boost," was downloaded millions of times and received very high user reviews.
Want a limited edition Usain Bolt gold iPod Touch? Too bad. The hot item sold out.
His $24 million in endorsement income as an active athlete (via Forbes) is likely to be a mere pittance as his running days wane and his brand spreads.
Flacco makes the list, not necessary because of post-career earning potential (which will likely be high), but because of good, old-fashioned prudence.
After signing a record six-year, $120.6 million contract, Flacco celebrated not with Beluga caviar and Cristal champagne, but with 10 Chicken McNuggets and some unsweetened iced tea.
And how does he get to the airport? In a private stretch limo? A giant gas-guzzling Humvee? Nope, he uses the free airport bus.
Remember, a penny saved is a penny earned.
But in the event that all that compound interest doesn't make him as wealthy as he plans, hopefully Haribo will keep him on as the gummy bear man for years to come.
Phelps, the winningest Olympic athlete of all time, has boundless earning potential. And if you think his popularity will wane as time passes on, look to Mary Lou Retton.
According to her manager, at the present (which is pushing 30 years after she became an Olympic hero), she is earning far more through speeches and endorsement deals than she ever did as an athlete.
And she doesn't have half of the international name recognition that Phelps now boasts.
Serena Williams has earned a pretty penny (actually about 2 billion of them, according to Forbes) as one of the top female tennis players of all time.
But her winnings and endorsements will likely just be the tip of the iceberg. Williams has her own clothing line, ANERES (Serena backwards), which distributes products in the U.S., Europe and the Middle East.
Jeter has made a mint from his baseball contracts.
But as his playing career reaches its autumn years, his entrepreneurial career will likely just begin to blossom.
Jeter already owns three 24 Hour Fitness Signature Clubs in New York City. But he also hopes to one day own a professional sports team.
"I’d love to call the shots, put a team together. That would be fun. That’s the definite plan," Jeter told Success magazine.
Considering the long and healthy post-Jordan-basketball-career life that Air Jordan shoes have had, The King could live out his days amassing more and more wealth by just sitting on his throne and signing off on new iterations of Nike Zoom LeBrons.
The first LeBron Nike product from way back when sold 72,000 pairs at $110 a pop, according to CNBC.com. In the first month alone.
The recently retired Beckham is more than a brand; he's nearly a currency of its own right.
Robb Young of BBC Culture predicts that Beckham will join forces with his fashion mogul wife to create a fashion dynasty.
Messi is already a legend to the entire world except for...the No. 1 global consumer: the USA. But he is slowly and cleverly beginning to brand himself in the U.S.
He recently played an exhibition game in Chicago and soon has another in Los Angeles. Organizers are taking full advantage of the events to help market Messi through various media channels.
Hilarious commercials like the Kobe vs. Lionel Turkish Airline one certainly help make Messi better known and admired among the nonsoccer loving Americans.
Also, Messi stands alone with David Beckham as an Adidas brand ambassador with his own signature line.
It's going to take a lot more than an extramarital affair scandal to strip Tiger of his long earning potential. Tiger has made millions in winnings but far more in sponsorships, appearance fees, investments and businesses, according to the Virtual HR Director.
Since the Tiger Woods PGA Tour video-game franchise was launched in 1998, it has amassed $754 million in revenue in the U.S. alone. You can be sure Tiger is taking a sizable bite from those earnings.
And then there is Tiger Woods Design, which designs golf courses around the world. Whereas once its projects were stalled, things now seem to be on rise again. The first Woods-designed course may open this fall in Cabo San Lucas.