A lot of pro athletes come from disadvantaged backgrounds where they haven't really become used to managing money beyond a hand-to-mouth way of living and then all the sudden they have tons of money in their laps that seems limitless. So basically a lot of them end up burning through it all and being essentially broke after their careers end.
I see where you are coming from but I think it's worth mentioning that a disproportionate amount of people born in the upper classes have also never had to manage their own money.
