‘Dark triad personality traits… thrive in zero-sum games where there are a lot of players, a lot being larger than Dunbar's number (~150). Under that number, it's hard to get away with dark-triad behavior because there's a collective moral intelligence at work. When in small-ish communities, dark triad traits are weeded out or at least marginalized. But beyond that number, most people know only a relatively small percentage of the people in the group and they instead have to back leaders based on limited information.’