Letter 27
The self-righteousness are the root of much suffering, both in the selfish person, and for those around them.
Self-righteous people love to punish and condemn, always looking for an opportunity to inflict something on someone who "deserves it." This creates a dynamic - someone is punished, they either withdraw or want revenge, we are all the less for it. Resentment grows, desperation spreads. The Pharisee gets their sadistic little emotional charge, and the rest of us pay the inflated bill for it.
Self-righteousness also allows the Pharisee to avoid taking any action on behalf of a person who has been injured, whether through any fault of their own or not. You can, if sufficiently determined, almost always find a way to blame the victim, and once you have found your excuse, you feel no more empathy or obligation. "Well, they shouldn't have been in that part of town!" "They shouldn't have bought a house in a 500 year flood plain!" And if the Pharisee can't find a reason that absolves them from any obligation to act like a human being, there's always "It's God's will," or the secular version, "It is what it is." Philosophers call it the "Just World Fallacy."
Of course, most people have an amazing amount of tolerance for the suffering of others, while being prepared to compose a symphony of whinging when they dash their foot against a stone.
If you are the sort of person who cares about avoiding this character flaw, there is a conditional watch you can put on your own behavior. If you find yourself looking for a reason to blame the victim, rather than seeking a way to alleviate suffering, then you are probably engaging in self-righteousness.
And if you are indulging a sick thrill from the sight of seeing someone "get what they deserve," then you might be better engaged in looking at your own lack of empathy for the fallen.
Every Inquisitor and Gestapo goon that ever was thought they were in the right. Don't be too sure when you go to enforce your justice.