I guess if we take any fighter and search for his story, then his life story would be worthy of a Netflix adaptation. People rarely go train any combat sport because of happy life. People rarely become a professional fighter only because they are good at beating other guys. Imho there is never a guy, whos parents were billionaires, and due to boredom, he began training martial art, all of a sudden he realises that he has a talent and becomes a champion. This is plot of a movie from 80s-90s only.
I don't think that would ever happen to some people who were raised and have everything they need at home and they can just simply ask their parents for everything that is a trend today. You can see how Manny Pacquiao's son fights and it looks like nothing from his father's talent even though he taught him well what to do. A person needs determination and high aspiration to achieve his honorable goals and that only happens if a person is raised in a harsh yet positive environment which leads him to dream and wants to be a champion one day. That's why in the tradition of the Arabs back then, they let their babies be raised by the Bedouin Arabs to make them strong at a younger age.
Rich people usually don't participate into sports because it's physically exhausting and they have the chance and connections to be behind the scenes in sport and still get as much money, if not more, as top athletes get. By the way, as far as I know B.J. Penn was rich before his fighting career. There we have Jake and Logan Paul brothers that were very reach before fighting. I don't call them fighters but still, it's a hard work and dedication to become what they become in fighting. On another hand, Bodybuilding is a very tough sport too, you have to say no to happiness to become a bodybuilder. Chris Bumstead, a 5 time Mr Olympia men's classic winner, is from Canada, comes from a pretty decent family. He was not a rich but not poor either and had a very high quality of life compared to many people. Besides quality of life, he is super handsome and could party all the day and attract tons of hot girls but instead he chose bodybuilding and become one of the greatest bodybuilder ever. But it's true that rich people rarely choose this path.