A lot of what you are saying rings true, but you may be underestimating just how small San Francisco is and how large the tech entrepreneur population is here. The number of new companies being started here is what makes San Francisco feel special. There is no other city on earth where you can overhear someone's new business idea at the cafe, the bakery, a restaurant, and the subway. And the crazy thing is that no one rolls their eyes at these ideas like they would in Chicago. It's pretty bizarre, sometimes unsettling, sometimes wonderful. It wouldn't happen at this frequency in Santa Cruz or Raleigh, or even New York or Austin or Boulder.