I think a lot of atrocities come from our need to be accepted by the people around us. Especially with fascists, whose group identity is based around excluding and hurting the outgroup, they’re stuck in a constant cycle of egging eachother on. One fascist says “lets beat up a black guy”, the others nod, and the person who feels most vulnerable to getting kicked out of the group tries to prove he belongs by saying “Nah, let’s KILL a black guy” repeat ad nauseam.