So you're saying black actors don't want to be successful because "black ghetto culture" will look down on them? Like they do Oprah, Denzel, Sam Jackson & Cosby? Oh wait, they don't. I dunno, but I'd assume if a black actor got offered a gig that paid money they're not going to not do it because Jerome from 125th St. might consider them a sell out. Without any inside knowledge of Hollywood and advertising, I'd have to take a wild guess that the reason is black actors aren't in high demand.
But you might be right, maybe they are getting offered tons of work but turn it down because ghetto kids will think poorly of them.