People “make it” and then forget to make their kids maintain it — this is a cycle as old as humanity. It starts with the natural tendency of parents wanting their kids to “have it better” than they did themselves.
The Chinese have a description of the cycle: the first one rises from poverty to “make it”, the second lives well but doesn’t build on the success of the first, the third one watches as his family declines, and the fourth is back in the poverty where the first began. There are exceptions, of course (esp. when it comes to those who basically force their kids to achieve, and so their kids often don’t learn how to be happy), but overall, the cycle is too often the case.
And those rich White southerners — they believe in having lots of kids…but mostly only when it comes to other not-so-rich White southerners. A few minutes before I saw your reply, I got a text from a cousin in Oxford, MS letting me know that that last of my grandmother’s siblings had just passed — she was one of thirteen siblings. The family was every bit as racist as you suspect, and they’re following that same cycle of more prosperity, less kids. This will sound callous, but in a way, I’m glad I have no more close family there, for now I have no reason ever to step foot in MS again — to someone like me, being raised racist and then realizing just how evil it is, it’s like someone who quit a lifetime habit of smoking walking into a room where everyone else is smoking — I see the racism there almost everywhere, the dog-whistles, the sidelong glances, the tone that carries meanings only heard by those who’ve used it before.