Presumably they all lead strange and traumatic lives that lead them to having radically different desires and values. Eg, they interviewed a previously incarcer

Presumably they all lead strange and traumatic lives that lead them to having radically different desires and values. Eg, they interviewed a previously incarcerated former gang member who said they felt it was as ethical as their previous drug dealing - presumably there's truth to that, but it's a view that's necessarily developed from a dark place. I'd like to caution you that trying to use evolutionary psychology to understand the existence of evil in the world is a path to madness. Kindness and empathy are an evolutionary advantage, our success as a species is predicated on our cooperation and mutual understanding. But that doesn't tell you very much about individual people. Most adults in my country are taller than 5 feet/1.5 meters, but I've met a couple adults that were 4 feet/1.2 meters tall. Outliers exist, and with 8 billion people, there are quite a few of them. I think we often feel a temptation to frame evil stuff in a larger context to make it feel smaller and more manageable and explicable. But we can get ourselves into a lot of trouble with narratives like that. Evolutionary psychology in particular is really easy to misuse, it readily leads to some prejudicial or racist lines of reasoning if you aren't very careful about how you define "fitness".