It's as simple as most of these people come from a WASP background and have a deep hatred for themselves. Anything not WASP in nature is good. Anything resembling the upbringing they despise is bad. They spend a lot of time building ridiculous mental models of the world that allow them to convert this overwhelming internal hatred of "the normal" into actionable oppression to stomp it out.

Hate is the key ingredient to the left. They are filled with hatred, malice, and anxiety and want to fundamentally change the world in hopes it will deliver them from their depression and angst.