Enslaving other humans, by and large, does not produce much in the way of cultural, intellectual, or moral benefit to the enslavers. It leaves one with a culture bereft of empathy, real morality, or — quite obviously — any sort of vision of improving the lot of themselves or other humans. It produces a culture of taking and hating.
As has been manifest by the last century and a half of postbellum Southern life and culture, despite multiple attempts to bring them into the mainstream of American life and values.
Worse, the southern racist diaspora has helped spread their peculiar and perverse brand of small-minded evil through the rest of the nation. (NOT that humans need that much ‘help’ being small minded or untrusting, don’t get me wrong. The south of the slavers did NOT invent human cruelty or evil.)