So what it is about being poor that makes a person good in sports?
I'm thinking both rich and poor play sports and some great ones come from both. Example Howie Long's sons. Wealthy family but the kids are also good NFL players.
The majority of the NFL is black because blacks often have excellent sprint speed and athletic ability.
Since most blacks are also poor it figures the NFL is filled with fast blacks from poor backgrounds.
Regarding combat sports like boxing and MMA it's a bit different. Why get your head beat in if your family is well-to-do? Lots of better opportunities like college.
Unless you really like fighting but most people would not do it when they can have an easier life.