In a word - emotion. To be specific, fear which is largely responsible for survival is a huge contributor. In general, Those who can manipulate others emotions

In a word - emotion. To be specific, fear which is largely responsible for survival is a huge contributor. In general, Those who can manipulate others emotions by triggering them can manufacture certain outcomes. If you create a environment of fear humans can do a lot of things that otherwise outside the context of fear would be unspeakable. Fear in the masses usually leads to confusion and/or convictions. Confusion is what allows bystanders to do nothing. Conviction is what allow doers to do.