What about the competition created by providing a Google advertising service to people from the same industry / business?

  You would need a substantial budget to dominate the Google Search Results pages - somewhere in the tens of thousands of dollars a week. Otherwise, you do not show up on Google every minute of every hour of everyday. So the concern about competition is not valid. If it was, Google simply wouldn't survive.

   Many new customers are often confused about why they cannot see their ads on the Google's Search Results pages. You will only find yourself on Google Search Results from time to time - this is all it takes to exhaust the average budget. This is how Google manages to share the exposure across the many advertisers competing for that space.