They are not failures according to evolution. they have enormous evolutionary advantages. Due to their low standing on society they breed much faster than whites typically do, and enjoy near immunity from persecution on racial grounds.
This is not about what nature favors, this is about human ideals. The ideal human is not a thieving, drunken, uneducated apeman. It's an intelligent, articulate, fair skinned human with a great degree of behavioral refinement.