I'll tell you one thing: I agree with Mr. Ouellette that somebody who makes it his calling to become an expert witness has to spend 24 hours a day on it, for the simple reason that if he doesn't, he's not an expert. He's not up to date on whatever is happening.
So in order to become an expert witness, you have to have, by definition, knowledge about a subject that is higher than that of the average citizen's. That is an expert.