Money in sports from various sources. 1. Advertising and sale of rights to TV broadcasts 2. Sponsors 3. Spectators 4. Sale of paraphernalia, T-shirts, sweaters, etc. Imagine the income from a FIFA World Cup match, if this match, according to statistics, was watched by one and a half to two billion people around the planet ... One match!
Athletes bring big profits from box office receipts, advertising, souvenirs. Accordingly, they want to be shared with them. It would be strange if the organizer earned $ 100 million on the fight, and gave 100 thousand to the main characters. And I think you screwed Mayweather's $ 400 million.
Pavel, you learned how to break bottles on your head - that means you are an amateur athlete)
You started doing it on a $ 100 bet - you are a professional athlete)
You have found a sports an agent who made an advertisement, found sponsors, rented a stadium / hall / arena, sold broadcast rights to different countries of the world. You got sold out and staged a show breaking bottles on your head - congratulations, you are a successful athlete, you are a star, your fee is $ 100,000,000))
Spectators who are watching all this. If we compare the proceeds from ticket sales, TV broadcasts, advertising and other things, plus the income of bookmakers, and the fees of the athletes themselves, it turns out that they still do not have such a large percentage.
There is also a criminal component : money laundering, kickbacks. In some sports - less, in some - more.
Since the world has entered the extreme phase of "bread and circuses", because of this, everyone who makes the most significant contribution to meeting this demand of the population receives corresponding dividends - actors, athletes, designers, fashion designers, etc.