1) Rage is like cocaine. It makes you feel powerful but it actually makes you weak and dependent. Once somebody becomes a rage junkie, furthermore, they will reliably do whatever they have to do to make sure that the target of their rage stays present and powerful, since they can't bear the thought of doing without their rage hit. Half the reason that Trump shrugged off four years of constant pressure and retook the presidency is that all the rage junkies on the left are so dependent on the high they get from hating him that they couldn't bear the thought of having him go away.

2) The classic sign is that the people who do it become what they hate. "What you contemplate, you imitate" is the keynote here; when people who insist they're fighting fascism act like fascists, you know they've been caught by their own incompetent magic.

3) Dion Fortune's rule is essential: build up what you support, don't try to tear down what you hate.