The Ralph Retort postulates that the root source of SJW behavior is to be found in shame:
Every SJW has something that they’re deeply ashamed of, something that makes them feel guilty or insecure, and this is the key to understanding everything else about them. You may have noticed that our enemies have enough skeletons in their closets to fully replenish the world’s oil supplies if they were underground – from pedos, to sibling sex-assaulters, to literal shit-eaters, to guys that think that rape is funny, to pedos, to guys that fail to report rape, to trannies that sleep with men without disclosure, to pedos, to women who abuse their boyfriends, to virulent racism, to pedos, to general all-around sociopathy – nearly all of these people’s lives are complete and utter trainwrecks, and this is no coincidence.
Of course, nearly everyone is ashamed of something, so that doesn’t explain SJWs all by itself. SJWs are made by how they deal with it. There are a lot of healthy ways to deal with shame, depending on the underlying reason for it. You can seek to improve your habits, you can repent and make amends to people you’ve wronged, you can seek forgiveness from God, you can realize that it’s nothing to be ashamed of and come to terms with it, you can find some escape to help you cope, etc.
But SJWs deal with it in the worst way possible, and that’s the factor that makes them SJWs. The SJW seeks to rationalize away their shame by pinning the blame for it on everyone else. “There’s nothing wrong with me,” they tell themselves, “I only feel bad because society has oppressed me with it’s arbitrary, regressive norms. In fact, I’m more progressive and enlightened that everyone else for realizing this. They should be ashamed! I should be judging them!”
From what I’ve seen, SJWs disproportionately come from the low-end of the social totem pole and the ugly end of the attractiveness spectrum. I suspect that gamma rage-against-society and ugly female rage-against-society also play a substantial factor in what motivates SJWs to behave as they do.