James Slack had an interesting idea about this, which makes a lot of sense. A lot of what Republicans do mostly (or only) benefits the rich. People like to cling to the idea that anyone can make big in this country, especially with the three L's: Las Vegas, Lawyers and the Lotto. So, a person may be mired in the lower class, but they think: "Hmmm... If I strike it rich, I don't want to pay lots of taxes either," and other such things. So they support ideals and plans they may never benefit them.
Also, they get bombarded with arguments that seem logical to people who like to be spoon-fed their logic. Here is my favorite example: "If we get nationalized healthcare, all the best doctors will get out of the business all the best potential doctors won't go into the business because they're only in it for the money." Who says that national healthcare can't pay doctors well? But the argument makes sense to them, so they'd rather continue to get screwed on their insurance.
I think the Republican base has more fear of diversity and seeks leadership who promises predictable ideology that does not change. Their need for maintaining this delusion seems to be greater than their other survival instincts.
Red, White and Blue
Me, Good; You, Bad