Most people have a hard time admitting when they are wrong. It is human nature to defend your position regardless of the evidence presented against it. That's why I have great respect for people who have risen to a point where they are able to simply say "oh, I see that I was wrong about that" and move on with their day. It truly is a rare trait.
Just look at the latest comments from Hillary Clinton (former Secretary of State, Former First Lady, Former relevant politician) for a very prominent example of this phenomenon.