Involuntary Celibate. Guys who can't get laid and aren't happy about it.
Depending on how you look at it, they're either losers worthy of mockery or the predictable result of a larger social shift that has devalued and emasculated men, leaving them angry and confused about their place in society.
Lots of press lately about "Incels" including an article I posted the other day from a lefty demanding speech codes to combat their message.
It would certainly explain leftists.