I feel like a big factor to the false uniqueness that many INFJs feel is out introverted intuition!! It's kind of hard to not feel as if you have some special purpose when you JUST KNOW things that the rest of the world can't seem to piece together.
I believe you’re right on the money! I figured Ni plus the focus on statistical rareness are some of the bigger factors into the false uniqueness belief.
I think Ni could also be largely to blame for the ‘know it all’ or ‘preachy’ vibe that INFJs can give off because it’s hard to find a balance between what your intuition is telling you and what is actually true. Even if we are correct most times we shouldn’t always assume that we will always be right. One of the problems with Ni is that sometimes it goes too deep, speculates too far, and jumps to conclusions. Ni doms often read too far into people’s behavior, trying to see some underlying meaning or truth behind what they are saying instead of taking words at face value. Sometimes Ni can see meaning where there is none. Someone may say, “I think you’re nice.” and our Ni might try to try to find some hidden meaning behind that by whispering things like “Wait why are they saying that? Are they lying and just trying to be nice? Or does this person have feelings for me? Who is motivating them to say this?” instead of just realizing that that person said they think you are nice because they just think you are nice. There’s isn’t some hidden meaning behind it all the time. They don’t secretly love you and are trying to show it in subtle ways or secretly hate you and are trying to deceive you. They just think you’re nice. Go home Ni, you’re drunk.
Sorry I went on a bit of a tangent there but the important thing is that sometimes we JUST KNOW but other times we think we just know and we’re actually very wrong. There’s a balance each Ni dom has to learn between when to trust Ni and when to question it. Personally, I know I need to listen to those ‘red flag’ feelings more often. I also have to be careful that I’m not seeing what I want to see instead of what actually is. I know if I find myself doubting something for a long time then that’s not a good sign. But I’m still learning! I’m sure I’ll make more Ni mistakes in the future and I’ll tell you guys all about them and how to avoid them :)
Stay humble and seek balance,