Human beings get angry when their wishes clash with reality.
That's the simple idea I would like to share. I came up with it seemingly randomly and thought that others might appreciate it or even learn from it. So, here it is. I think it might be best to leave it this way.
What? No. Humans become angry when they feel wronged. Anger is a good, healthy emotion that helps define our identities. It allows us to judge what might be good for us and what we don't like to see or experience.
Whatever you think about reality or clashing with some sort of metaphysical realm ... I think that is a really misguided, unhelpful view.