I think that MBTI may attract people who are different or eccentric. I will not debate about whether these people would be labeled crazy or not. I suppose everyone is different, but some of us are more different than others.
If some one is average or normal, they probably never stop to think: "Why am I am normal?" or "Why am I fortunate enough not to struggle with fitting in?"
I can't speak for everyone, but I spend lots of time thinking things like "Why am I different?" "Why is it my brain doesn't seem to function the way most people's do?" "Why is it so hard for me to fit in?" "Is this a mental problem or just a difference?" I imagine it was this way for other people who are different as well, or at least some of them. Some people act like I made a deliberate effort to be different, like this was a choice I made. It never felt like a choice to me. It just felt like being myself.
I have looked at various material - psychology, pop psychology, self help and New Age - to try to answer some of my questions. Of all the different material I look at the best sources to answer my questions have been personality typing. It gives me answers: I am different because I am a rare type. My brain doesn't function the same as most people's because I am not the same type as most people. It is hard to fit in because I am a different type then most people. It isn't a mental problem, it's just a different type.
I admit, I have some eccentricities that are not accounted for by type, but it does account for many of them. Difficulty expressing feelings, day dream quite a bit, percieved as not social enough, difficulty putting ideas in words - that is just a "normal" INTJ.
Ilah