1. Just because someone shows some intuition that does not mean that the person is actually an N.
2. Every so called celebrity has a number of his/her people in .... I will call it a background. So it is highly likely that most of N in some famous people comes from the fact that some people in the background are Ns.
On the one hand, N is likely overassigned. On the other hand, out of my S and N friends, most of the SPs would briefly check a place like this out and then move on and many of my SJ friends are disinterested in anything about MBTI unless there's a practical reason for them to consider it (eg relationship on the rocks). The NTs generally are a so so hard sell (depends what other ideas they have cooking right then. They certainly wouldn't do it just because I'm interested in it usually), and the NFs I have been friends with generally were very interested. I actually would be interested in starting a sensor thread to find out what brought them here initially and why they've remained.
Personally, I think it would be cool shit if I were ESTJ or ISTJ rather than ENFP (e.g. same cognitive functions, but the other way around). In fact, I was one of the very few on here who answered the poll, "I wish I were S, but I'm an N." So I don't want to be part of some allegedly elitist what-the-fuck-ever.
That being said, I don't really think it is all that elite. In a population of nearly 6,000,000,000 that means there are approximately 30,000,000 INFJs. Could it be...in some strange coincidence, that 200 of those 30,000,000 happen to hear about MBTI, get interested in it, find out about typo c, and come here? Um, it 'ain't' that far fetched, now is it???
Sure, people get mistyped. Sure, people wanna be special. Sure, people want to escape from the drudgery of everyday life.
But does that mean 80-90% of people here are mistyped? Could be. Probably not. I'd say rough estimate 0-25% mistyping rate could be reasonable.