But maybe loneliness causes fascism. (Or at least it creates fertile ground for it.) Lonely men, in particular, looking for somewhere to belong, that nobody else accepts, seem to me to be ripe for fascists to recruit.
I'd rather be lonely than a fascist. It's not a pipeline. Fascism may try to exploit it. But you are responsible for you: not someone else. Loneliness doesn't turn someone fascist. Fascist tendencies cause loneliness, if anything, not the other way around. No sane person likes those tendencies.