They actually don't have self love, never having experienced love as children. They are very insecure and lash out at people in anger, having to hurt others as others have hurt them growing up at home. A need for constant validation, like he does, deflecting blame when it's pointed at him. The boasting is covering up his self loathing, his parents likely rarely ever showing any real affection. There is no real cure, and will hurt anyone that gets close, usually picking on good people who try to love them. Much like the actions of a few trolls here, who will try and enlist others in their game, although those others will also eventually be victims as they have no real friends. The covert is the worst, acting loving and innocent in the beginning, especially to others as a facade, until they have you secured, then turn against you, becoming the real them, but the malignant like Trump does it openly, and with his money, gets away with a lot until he has real evidence against him.