The Olympics drive athletes to get ever faster, higher, and stronger, to quote its Latin motto: "Citius, altius, fortius." But while the Games show athletes at the peak of human potential, it rarely does much for their earning potential.

Every Olympiad, it seems, sees a new crop of athletes become celebrities, their names and faces recognized by millions. Reaching that point requires staggering amounts of time, focus, and discipline with money. "You have to throw everything into it, and it becomes a kind of obsession," says Craig Leon of the Warsaw Sports Marketing Center at the University of Oregon. Yet it brings little wealth. "For a lot of Olympic athletes, there isn’t a lot of money to be made," he says. In fact, the Olympics can hurt an athlete's earning power.

The biggest impact is lost earning potential. Training for gold leaves little time to train for a career. "When Olympic athletes decide they’re done, and they’re in their late 20s or early 30s, they’re ready to hop into the working world. But their work experience is often little to none," says Leon, a marathoner who once made it to the Olympic trials.

Olympians can earn a living on prize money, sponsorships, and speaking engagements, but not everyone gets that chance. And US athletes don't receive the government support paid to their competitors abroad. They rely upon stipends—sometimes as little as $400 monthly—from the governing board of their particular sport. Medal winners receive a bonus of as much as $25,000 from the US Olympic Committee, but beyond that, there isn't much. Olympic sports rarely provides a decent income to anyone but the biggest stars. "It's such a crapshoot," Leon says.

Of course, few athletes do it for money. Still, they need ungodly amounts of it to succeed, and lots of times, it never returns. Here's a look at the economics of some of the biggest sports of the Summer Games.

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Swimming

Expenses: $100,000 per year

Training: 8 to 12 years

Famous Olympian’s worth: $55 million (Michael Phelps)

The equipment can cost hundreds of dollars a year, and that's just a start. Michael Phelps trains at the Baltimore Aquatic Club, where annual membership fees run $1,500 to $3,000 a year. Swim meets can incur $5,000 in expenses, and competitors attend around four annually.

USA Swimming, which earns $100 million in registration fees from its 300,000 members, is among the most generous governing boards. Swimmers ranked 16th or higher receive a monthly stipend of $3000, and the organization gives collegiate swimmers about $1,750. Gold medal winners earn a bonus of $75,000.

Swimming is among the most high-profile sports of the Games, with star swimmers often earning big endorsement deals. If you're (very) lucky, you might even become the next Michael Phelps. Today, he's worth $55 million.

Track and Field

Expenses: $20,000 per year

Training needed: About 4 years

Famous Olympian’s worth: $60 million (Usain Bolt)

Track athletes can burn through at least six pairs of shoes a year. Equipment costs add up quickly, as do medical expenses and the cost of training and competing. Like many athletes, those who compete in track and field must work part-time while chasing gold. Triathlete Gwen Jorgensen worked 65 hours a week as accountant at Ernst and Young, eventually shifting her time to spend more of it on training than working. Now she's a favorite to win the gold medal.

Track and field isn't especially lucrative. According to the USA Track and Field Foundation, only half of track and field athletes ranked in the top 10 of their sport earn more than $15,000 a year from competing. Injuries can put endorsement deals at risk. And while it's possible for top competitors to earn more than $1 million annually, it’s rare.

Gymnastics

Expenses: $18,000 per year

Training needed: 10 to 12 years

Famous Olympian’s worth: $3 million (Gabby Douglas)

Gymnastics is remarkably glamorous, and frightfully expensive. Top competitors start training as young children, and training can cost more than $12,000 a year for a dozen years or more. "Gymnastics is an expensive sport," Natalie Hawkins said when she filed for bankruptcy just months before her daughter Gabby Douglas won two medals during the 2012 Summer Games in London. According to one training center manager, gym time alone can cost about $600 a month, and competition outfits can cost $300 to $500 apiece.

USA Gymnastics helps cover costs for gymnasts who make the national team, and the USOC also hands over more money to higher-profile sports—like gymnastics—which tend to win the country more medals. In 2012, the last Summer Olympics, USA Gymnastics said it gave out more than $4.2 million in direct payments to its athletes.

Sponsorships help top gymnasts, but the competitive cycle can be brutal. For many, the goal is to peak as an Olympic event gets underway, at around 16 to 18 years old.

Tennis

Expenses: $150,000 to $500,000 per year

Training needed: 4 to 8 years

Famous Olympian’s worth: $150 million (Serena Williams)

The best tennis players start early—Serena Williams was playing at three—and competitive players can spend $50,000 to $150,000 a year on travel expenses alone, according to one pro tennis coach. Training and gear add many thousands more. Grants and stipends from the United States Tennis Association, meanwhile, can be comparatively minimal, ranging from around $2000 to $4000.

Still, the payout can be great. Williams—the best female tennis player in the world—is now worth $150 million.

Granted, her fame and fortune didn't come from the Olympics—despite her four gold medals. The same is true for players on the US men's basketball team. For some athletes, the economics of the Olympics just doesn't matter.