I've been thinking about all this for a while now, and my current thesis is that these people are not so much stupid as desperate to believe a horribly bigoted thing, and the Murdochs et al., are very good at telling them the thing they want to hear.
@DyDave there’s an appeal in NOT being a part of a society that can’t look after itself, and of which solidly half are insane or staggeringly stupid.