So are you saying that because some have made it marginalization is not a thing? Of course its causes are also cultural, that is exactly my point: we need to find cultural answers to this.

Your argument smells a lot like the self-made-man American myth. Just because some have made it out of poverty, often in different conditions than these, doesn't mean we don't have to fight poverty because everyone who is smart enough will pull herself out of it by her bootstraps (and I'm not talking just about material poverty).

I think you are assuming consciousness (of the group) where can be none.

Shouldn't be in the interest of the majority to make sure that minorities are not marginalized?

Well… I don't know how to say this: but if at first it sounded hollow, this talk of ethnic subgroups and culture makes it sound rather racist.