Politics.
Democrats won in 2008 and 2012, and while if only whites voted in 2008 Obama might still have slipped by, it was clear in 2012 that Obama would have suffered a crushing defeat had it not been for minority voters.
So first of all, democrats began to think that white voters didn't matter anymore, and secondly, they began catering to anything and everything that was pro-diversity, pro-minority. Defending Islam blindly, black lives matters, no respect for borders or security or any kind of immigration "reform".
It bit them in the butt, and now they have zero power. They have been bleeding white voters since the 1960s and it is only getting worse.
They realize this, and have begun to resent white voters.
The $hitposting thread is over there -----×
The admittedly this fits well into a thread named after Sam Spade