We Know Them Better Than They Know Themselves

I often struggle with accepting certain characters in stories. It's usually the ones that do something so stupid that all I can think is, what kind of moron can't see that they are going to get themselves into exactly the trouble they should be avoiding? The answer usually is, the kind of moron that does not spend all their time analyzing themselves.

Literary types tend to be observers and thinkers. They spend their time considering a character's actions, the repercussions of them, and then discussing it with other people who have done the same. The characters of literary canon have been analyzed to the point of exhaustion.

But those characters have not analyzed themselves. And when you realize that they are usually just human (or humanoid), and that they are not terribly introspective, it makes sense that they might make some really stupid decisions. With any luck, by the end of the story, they will have realized how stupid those decisions were.