Here's an interesting post with some thoughtful observations about being an "expert"  . 

I think it's true that everyone is an expert in some field or other.  But most people aren't egomaniacs, and so just use their expertise quietly and/or offer it for free.  Those professional experts and gurus who claim they know heaps usually don't know nearly as much as they think they do. 

I once saw a big-name motivational speaker deliver his spiel to an organization I was working for.  Must have cost them a packet!

He was energetic and a good performer -- also supremely confident.  But most of what came out of his mouth was just a mess of cliches.

Couldn't help thinking that his whole act was just some kind of scam.  But in retrospect I realised it wasn't.  He genuinely believed that he had earth-shatterring revelations to offer that no one had thought of before.  That made him kind of sad in my eyes. 

(Still, he was an expert in one thing:  using his unlimited ego to trun his limited knowledge into piles and piles of money.  So, I do have to hand it to him for that.)