This started out as a comment in response to Punzki's comment, but it was getting too long.

Punzki, I'm sorry to say I don't know you well enough to reassure you one way or the other.  I'll say this, though: all of us fall into that category--even me.  We can all be pretty blind. We can all be proud and haughty and insufferable. 

I think some people just have more "right" to be in that category than others.  If someone with clearly limited abilities struts around like a peacock, it's easy to make fun of him.  But when someone with an established name and reputation, and a track record of good work starts believing in his own greatness, it's difficult for those around him to help him regain perspective.

My measure of how far gone a person is is simple: Are there people in your life who tell you that you are becoming too full of yourself?  If the answer is yes, then you're still connected.  If the answer is no, then let me at least say that it's probably not because it never happens.