They're desperate to be important, to be the stars of their own real-life, self-insert fanfiction, and you can't be a hero in one of those without a villain. And, as has been pointed out numerous times beforehand, the demand for racism, fascism, and all the rest far exceeds the actual supply. So they need to either find it (a difficult task in light of the aforementioned supply issue), create new sources of it, or just convince themselves that everything that they don't personally agree with and support is it.