Most people choose a sport at an early age, driven by their passion and love of the game. Few people start playing tennis or soccer to get rich, but there are many people who have become millionaires because of their passion. At a time when tennis players want to increase their earnings, and sports stars seem to be earning more than ever, it’s worth examining the gulf between sports.

If you examine a list of the world’s richest sportspeople, you start to realize that there are certain sports in which it’s so much easier to earn money if you’re a star: boxing, football, soccer, tennis, golf, basketball, baseball, racing and cricket. At the same time, there are certain sports where barely anyone can make it onto a list of the world’s richest ath letes.

Think about the people who have reached the pinnacle of judo, fencing or high jump. They may have gold medals to hang around their neck, but they probably don’t have a Ferrari parked out front. The best curlers and bowlers may make the occasional appearance on TV, but they don’t have legions of adoring fans or multi-million sponsorship deals with Rolex. At the same time, Floyd Mayweather’s earnings are pegged at around $80 million annually, and Roger Federer makes a bit over $50 million.

Many people assume that soccer players are the richest in the world because the sport has such wide penetration, and a truly global audience, but you need to get quite far down the list before you will come across a soccer player, which is David Beckham at number eight. The English midfielder is 37, which is beyond the age where anyone can play their best soccer, but he is still a powerful force on the field. But the majority of his wealth actually comes from c orporate sponsorships, and not from his famous free kicks directly.

“The biggest earners are usually boxers, because they get a big cut of pay-per-view revenues, from events that are watched around the world. They have no teammates, no stadium and very little fixed costs – so there’s so much money that goes directly to the boxer,” said soccer tickets retailer StubHub. “Soccer players have a much bigger profile, and there are more of them, but – when it comes to money – the best soccer player is going to be knocked out by the best boxer.”