>>24718140
De sade was a sadist, literally. He beliefed people should die and suffer to the maximum possible. Overall its an anti-life attitude and an evolutionary dead-end.

>>24718140
because he has his characters talk about how cruelty is natural in a "philosophical" way, i.e. multi-page rants, much in the same way that Ayn Rand has her characters talk about how money is good
the difference is that Sade's villains are, at least in part, satirizing French nobles who would abuse their power, as if to say "here's how these people would describe their morality if they were honest"