Its the simple fact that many fighters are forced to doing so from poverty, although less now days. Some people in this sitiutation e.g. Bernard Hopkins keep every cent fro fear of going back to the old way. Others react by spending to get everything they never had. People always react different when they get money, some people jus cant manage money.

To say its eclusively Afro-American boxers though is pretty ignorant.

One example off the top of my head. Do you think Henry Cooper would ever really do adverts for awnings if he had a bit of money tucked away?