Facepalm

Having gone through an incel phase myself when I was younger, It's frustration and insecurity about not being able to get attention from women and then projecting any negative experiences they have or hear about other dudes having onto all women. That's easier than putting themselves out there and trying to form relationships and potentially facing rejection. Then they go online and reinforce each other's beliefs instead of trying to lift themselves up.

I'm very glad I was able to make friends with better people and get myself out of that mindset. Admittedly I'm still single now but I have a lot of female friends that like me as a person, which is nice.