I think an important thing to remember is that when white people think about "the good old days" of the 1950s, they're not thinking "everything was great for white people back then, I wish we could go back to oppressing blacks!", they're just thinking "everything was great back then!" The black-white thing doesn't even figure in their minds. It's just not a thing. Because of the way that many white people have absorbed the ideology of liberalism, they already believe the US to be (or have been) a meritocracy. The extent of their feelings about minorities having been oppressed in the past is "Well that sucks, but that's over with now." They don't see it as "we had privileges because they were oppressed", they see it as "Everything was normal for us and unfortunately bad for them." Racism, sexism, etc. to them, are personal issues and not a systemic issues, so there's nobody to blame but the oppressed themselves if after "racism/sexism ended" they couldn't "help themselves".
What happened in reality is that capitalism became globalized, Reagan began destroying the labor movement, and technology helped crush the working class without properly reimbursing them (as would happen under socialism). And this happened at the same time that non-white-male people in the US started demanding their fair share. These two things are not related, but the capitalist class used the latter to deflect from the effects of the former. In essence, the way that white people are raised to think about it is "Everything was great and normal...until those women/blacks started tearing town the society that we built and those Hispanics started breaking the law and streaming over the border and taking our stuff!" They see themselves as being "normal" and trying to live according to "the rules" and the other people as trying to bend the rules or change them to their favor and, most importantly, with the purpose of making things worse for whites. This is obviously nonsense but that's the way that white people conceptualize it, because that's what they've been taught. Everything was great and normal (and sure it sucked for some people but that was an outlier, not intentional) and then the liberals manipulated minorities and women into destroying society so they could carry out their godless socialist revolution. The reason they reach out to Trump is because he's not afraid to say the things they're thinking, whereas the GOP establishment - which still retains some measure of non-insanity - doesn't want to completely 100% utterly and totally destroy the possibility of it losing future voting blocs. To these people though, this simply means that the GOP establishment are in cahoots with the liberal elites. They don't see the class issue behind this at all, so they follow the billionaire who tells them what they want to believe.
The only way to combat this is to combat capitalism directly since that's what is causing the crisis, and even doing that won't wipe out the racism/sexism/all the other -isms that have been compounded since it's become so deeply ingrained now.