At the rate that rival political cults are going at each other these days, how does our species avoid a scenario where we just start killing anyone who disagrees with us?

Ironically, we buy guns to deter that. Typically it’s governments that start killing by the millions, whether it’s radical left or radical right (but numbers wise, usually left, unfortunately). They can only do it after they either disarm their populations by force or coercion, and slowly take over the education system to indoctrinate millions of kids who have no concept of being disagreed with.

As much as I would like a world where nobody felt the need to have guns, we currently do not live in that world. A couple hundred million armed citizens is a great deterrence against that kind of thing – its worked well so far.