The radicalization of the lonely, aimless and disaffected young male.
Don't forget that from the outset, Gamergate was part of Steve Bannon's plan. He knew he could cultivate a disaffected, young male online audience into a hate mob and point them towards fascism. Gamergate was one symptom of that path.
Bannon briefly partnered with IGE which made real money on the purchase and sale of digital items in World of Warcraft. It was there he saw an audience that could be cultivated.
And Milo Yiannapolos was hired specifically to groom that audience to the type of audience Breitbart wanted -- torch wielding anti-leftists.
There's absolutely no surprise that a vast majority of this audience, despite self identifying as left leaning libertarians, were huge advocates for Trump.
It became this collection of a whole bunch of toxic subcommunities like MRAs, PUAs, channers, etc... and made them coalesce into one group dedicated to anti-leftism.