Cruelty links to the belief that I myself and others like me are righteous and those despised others deserve pain:
"What Serwer understood though—and which I think sometimes gets lost in responses or summaries of his argument—is that cruelty is intimately connected to a sense of virtue, empathy, and community. Fascism creates a structure in which sadism feels righteous and cruelty feels like the natural complement to empathy and solidarity."