actually try to do something about it (even if you fail or it takes a lifetime or not always possible), or just stay angry

In my experience, these are conjoined. You try to do things (or, at least, stew about wanting to do things) while you're angry. And as the anger fads, the impulsive need to act fades with it.

So then you've got a group of people who are still angry. And they can turn to the people who have burned out from their anger and scream "Why are you not still angry?! Why are you so apathetic?!" And then these angry people can blame the burn outs for whatever failures accrue.

But it goes one step deeper, because there's no just one group of angry people. It's a melting pot of people with different views all competing to impose their will on the world. And any time any individual or group fails, they need to root out the cause of that failure. Which means blaming the out-groups and self-flagellating over personal weakness and bemoaning the neutral third parties for not being on your team.

Also, lots of money in selling people an outlet for their rage. Or selling them a cure for it. Or selling them a means of inflicting pain on the people they're angry at. Or just selling them on the promise of some future satisfaction.

An endless conflict fueled by rage, fear, greed, and ambition.