Only half joking: there was this one fanfic you see…
Mainly I don’t think there was any one inciting incident beyond its creation: Yud was a one man cult way before LW, and the sequences actively pushed all the cultish elements required to lose touch with reality. (Fortunately, my dyslexic ass only got as far as the earlier bits he mostly stole from other people rather than the really crazy stuff.)
There was definitely a step-change around the time CFAR was created, that was basically a recruitment mechanism for the cult and part of the reason I got anywhere physically near those rubes myself. An organisation made to help people be more rational seemed like a great idea—except it literally became EY/MIRI’s personal sockpuppet. They would get people together in these fancy ass mansions for their workshops and then tell them nothing other than AI research mattered. I think it was 2014/15 when they decided internally that CFAR’s mission was to create more people like Yudkowsky. I don’t think its a coincidence that most of the really crazy cult stuff I’ve heard about happened after then.
Not that bad stuff didn’t happen before either.^___^