"How does one rest at night after doing that?"

I have read that <3% of people just have no conscience. They don't see people as like themselves, but merely as things. Things can be made to to amusing things, like beg for mercy, or squawk when poked or prodded just so. Psychopaths are incapable of socialization, and narcissists, something most psychopaths are, are immune to criticism. So I've read. I can't relate either.