Some people have such a fragile ego, such brittle self-esteem, such a weak "psychological constitution," that admitting they made a mistake or that they were wrong is fundamentally too threatening for their egos to tolerate. Accepting they were wrong, absorbing that reality, would be so psychologically shattering, their defense mechanisms do something remarkable to avoid doing so — they literally distort their perception of reality to make it (reality) less threatening. Their defense mechanisms protect their fragile ego by changing the very facts in their mind, so they are no longer wrong or culpable.

People who repeatedly exhibit this kind of behavior are, by definition, psychologically fragile. However, that assessment is often difficult for people to accept, because to the outside world, they look as if they’re confidently standing their ground and not backing down, things we associate with strength. But psychological rigidity is not a sign of strength, it is an indication of weakness. These people are not choosing to stand their ground; they’re compelled to do so in order to protect their fragile egos. Admitting we are wrong is unpleasant, it is bruising for any ego. It takes a certain amount of emotional strength and courage to deal with that reality and own up to our mistakes. Most of us sulk a bit when we have to admit we're wrong, but we get over it.

But when people are constitutionally unable to admit they’re wrong, when they cannot tolerate the very notion that they are capable of mistakes, it is because they suffer from an ego so fragile that they cannot sulk and get over it — they need to warp their very perception of reality and challenge obvious facts in order to defend their not being wrong in the first place.