There were wealthy African-Americans before the Civil War. There has been a privileged layer long enough that the phrase "Talented Tenth" was coined for them back at the turn of the twentieth
century. SF fans might be aware of Samuel R. Delany's family background from his autobiographical works. Not too long ago, the Sanaa Lathan/Simon Baker film Something New put some of it on popular film. ER is a little older, but the Angela Bassett/Courtney B. Vance characters came from the same milieu.
It is of course true that as yet no African-Americans have as yet reached the extraordinary heights of the Rockefellers in their heyday. But I shouldn't be surprised if some have indeed reached the levels of a Hilton.
PS My belief is that DuBois wouldn't approve every self-assignment to the "Talented Tenth."