I'm truly convinced that a huge part of this was moot leaving 4chan in 2015. Nerd culture has always been misogynistic and insular, but it never seemed politically focused until the past 10 years. It used to be more unfocused horribleness. When moot resigned from 4chan, there was a genuine white supremacist plot to gain moderator positions and push fascist rhetoric. It worked. All that ambient horribleness became laser focused and more coherent.

Also probably a lot more to do with material conditions honestly. The fraying economic features of the 2008 recession were never truly fixed. People no longer believe in a future and it became harder for nerd culture to act as an escape. Everyone's more stressed, more pissed off, and more vocal. With nerd culture the ambient feelings got pushed forward as the things themselves ceased being enough of a draw on their own. More frayed and deranged types started demanding their misogynist, white supremacy be reinforced more aggressively, in every moment, by all media.