I used to think some personality disorders managed to hide themselves from those who had them. I used to think this because people with very obvious personality disorders would tell me that there was nothing wrong them, that there was something wrong with me. The more I talked to people, and learned about them - the more they spoke to me about their near-identical personality disorders - I realized what the difference was: intellect.
Smart people conclude the way they think/behave is incongruent with reality, and choose not to continually feel at the mercy of themselves as if the entire universe were against them. When smart people know something is wrong with them, smart people seek help. From what I've read, various behavior therapies help to completely remove 90% of smart people's personality disorders and helps them successfully compensate for the last 10%. Conversely, its seems to me that behavior therapy decidedly does not help not-smart people at all. Mostly because not-smart people think personality disorders are bullshit.
Its a perplexing world we live in.
"The wise man doubts often, and his views are changeable. The fool is constant in his opinions, and doubts nothing, because he knows everything, except his own ignorance" (Pharaoh Akhenaton, c.1250BCE)