In my skim of the two posts I didn’t get to any suggestion of “used to be favorable, then realized they’re led by duplicitous misanthropes” as a pathway.

What about: “read a particular HP fanfic to try and fit in with a new crowd, was utterly repulsed by the narrative voice, discovered later it was part of what seemed like an elaborate cult that was weirdly sensitive to sneers, and finally found an outlet for their nerd bloodlust”