Several mass shooter manifestos have made references to the parties you’re talking about… but they end up killing their families, school children, or shopping centers full of minorities instead.

I suspect it’s because most mass shooters are ultimately cowards and those organizations are big, scary, and often located in “intimidating” areas like major cities. That, and there’s tons of racist conspiracy theories that make it sound like a bunch of working class Muslims, Blacks and Latinos are somehow playing for the same team as Jamie Dimon.