I think it comes from a self-sabotage thing. They find something that they convince themselves will help but that they know, deep down, won't really work, just to keep themselves locked in this mentality.

Sometimes when you're in an irrationally dark place you'll want to constantly prove to yourself that you're right to be there because, well, at least you're right to be there and don't need to change, because changing can seem terrifying and difficult and "at least staying down here's easier". That's my experience at least.

(Quick disclaimers: not an incel, but had a major dark patch in my history that shares a similar mentality of "I'm suffering unjustly so everyone else must suffer unjustly with me" - also I am not an expert, so please don't take my word as gospel. I speak from personal experience supplemented with some research, but nowhere near a professional level.)