You're reinforcing the parent's point that there's not race discrimination but class discrimination. Our hypothetical white billionaire is presumably discriminating utterly on a class basis (hanging out with zero poor people of any race) and not discriminating at all on a racial basis (hanging out with members of his class in proportion to their race / without racial bias).

You missed the "black billionaires / white millionaires" distinction.

I did, my mistake. In that case I'm skeptical of your premise (that white billionaires hang out with white millionaires but not black billionaires).