Actually it's that people don't forgive themselves for being wrong. They knew they were wrong at the time but choose to ignore it for some reason. Usually because they simply want to believe something else more and play the dumb game of pretending that something is real makes it real.

It's why people get mad when you tell children Santa Claus isn't real. They don't like it when you tell their kids the truth because it ruins the little game they are playing and outs them as the arbiter of who is naughty or nice. So it's not Santa's fault you didn't get a pony for Christmas, it's your parents fault. The parents rather than blame themselves for lying to their kids would rather get mad at the person telling their kids the truth about the world than dare to admit they lied.