You kinda missed part of my specific point,

Mostly that there's a lot that goes on in society where a single person can't necessarily genocide a 'race' but a single person can certainly fuck up a single person of family's life over the long term intentionally and not care, even if doing so does not gain them any real advantage.

But hey if you want to look at 'bigger picture', 'societal' cruelty...

Reaching even further back than WW2, we may look at the Armenian Genocide and the circumstances.

> You don't need to invent instincts or tendencies or claim something is more subtle or targeted when the vastly simpler explanation is just that it's all just cost-benefit.

Part of the human condition used to be the idea that we had evolved beyond short term cost-benefit, however the last 15 years, might be proving you right.