The ‘Expert’ or Expertise?

I have read articles and comments recently explaining the virtues of becoming an expert in your industry field — or even part thereof. And how this in turn is good for business, since (logically) people will turn to you for your help when they need it. That does sound well and good… perhaps in theory. I was just wondering how many people are in any given industry? Is everyone meant to take this advice and become an expert?