Think of this mathematically. We did something very wrong at time T = 0. It is a matter of fact that economic wrongs are self-perpetuating and long-lived. Thus, at time T = 450, you can isolate, statistically, some economic disadvantage in any black person who can trace their lineage back as being affected by that original wrong at T = 0. It doesn't matter how rich they are--they would be incrementally richer had that wrong not occurred.

At the same time, the poor white person benefited from that original wrong, and you can isolate, statistically, some economic advantage to him tracing back to that original wrong. It doesn't matter how poor he is, he would be incrementally poorer had that wrong not occurred.