I think it's a bit (ironically) disingenuous to call them stupid; they're just as smart as everyone else which is why it's so terrifying that they actively vote against their own best interests. They do so because by hurting themselves, they are also hurting the people they want to hurt and exclude. It's why they don't want healthcare for all, or free tuition, etc., that means 'ethnics' get it too, and they don't want that.

"They'll shit themselves just so you'd smell it."