As someone with a close relative who is deep into the Q-Anon stuff, and was totally normal beforehand, I can't help but see how similar it seems to psychosis, or at least severe delusions that you find in people who are psychotic/schizophrenic.

It's truly shocking to witness someone you've known your whole life just go off the deep end into something that has so many demonstrably false aspects, and watch them start saying believing so much batshit crazy stuff. I don't know of anything comparable, short of a previously typical person developing a severe meth addiction, which is known to cause psychosis.