In their world view, there are only "oppressed" and "oppressors". There is nothing else.
Unfortunately, many find this simplistic view of reality to be attractive.
With socialists though, they are the true oppressors, but with the way they operate (the dialectic), they always frame themselves as the oppressed.
This way they can all run on hatred and anger and their calls for violence can appear to be rationalized as righteous anger and those receiving it, deserve it.
And this is also why they can never be content or happy.