> when you steep people in a culture that tells them someone is (or their ideas are) an existential threat, eventually someone is going to be the right level of scared + unstable that causes them to kill people to try to defend their way of life.

Well, yes. People point this out regularly with mass shootings. Sometimes the shooters helpfully leave a list of all the violent rhetoric that inspired them. Anders Breivik claimed to be acting against an "existential threat". Those words get used a lot.