The Regressive Left certainly has played a role, not only in the rise of this crap but in the election of Trump, with the way it has shoved PC and Identity Politics down the throat of the country. And no, they can't be surprised at the pushback (although I suspect it's a hell of a lot stronger than they imagined).
They don't care. They think that between white left wingers and demographic changes it won't matter. That's why they're not putting any effort into actual race healing.
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I had long discussions with Rightwinger, on this issue. His position is pretty much as you describe.
He literally expects for White Americans to be completely marginalized, and increasingly discriminated against, and to just take it, without complaint.
Well, he DID expect that.