They get the Two Minutes Hate from 1984 pumped into them every day, for far more than 2 minutes, via traditional and social media for years and years. They're so deep within propaganda they can't see themselves as the monsters* they have become. That doesn't excuse it of course, but it can explain it.

The horrible thing about the Two Minutes Hate was not that one was obliged to act a part, but, on the contrary, that it was impossible to avoid joining in. Within thirty seconds any pretence was always unnecessary. A hideous ecstasy of fear and vindictiveness, a desire to kill, to torture, to smash faces in with a sledge-hammer, seemed to flow through the whole group of people like an electric current, turning one even against one's will into a grimacing, screaming lunatic. And yet the rage that one felt was an abstract, undirected emotion which could be switched from one object to another like the flame of a blowlamp.

https://gutenberg.net.au/ebooks01/0100021h.html#ch1