It all comes back to fear, though, doesn't it.
Fear of losing my place or "status" in the world. And if someone comes along (Trump, Boris, Farage, whoever) who offers answers and an outgroup to dump the blame and fear onto, well then, that's very comforting isn't it?
If I've never had the chance to develop some critical thinking and I feed my brain with FB memes or Jeremy Kyle or Fox News (or whatever brand of poison you like, there'll be one for every nationality, age group and income bracket) then I will believe the poison that I'm being fed.
Which starts up a vicious cycle of reinforcing "othering" beliefs.
It's quite comfortable to blame the Jews, or the EU, or travellers/gypsies, or Catholics or Muslims or people on benefits.
It gives me a sense of being part of a group who disapprove of "that sort of thing". So, there's bonding with "people like me".
It gives me a target on which to displace my fear or sense of not being good enough. So, I feel better about myself and my place in the world.
These are very natural human reactions, to which we are all prone.
It's quite uncomfortable to contemplate this, and to realise that I am prone to it too.
But, the reality is, that unless we spend time thinking about this, then, yes, we are all potentially an Amon Goeth.
Evil is banal and ordinary, and lives much closer to us than we imagine.