The thing is - normal economics don't apply to a game of hype, brand and relationships. The top funds, the press, the special talent, the specialized talent,

The thing is - normal economics don't apply to a game of hype, brand and relationships. The top funds, the press, the special talent, the specialized talent, the customers, the early adopters, yada, yada. When everything is in 'one cluster' - there is a very good reason to be located there, and it almost always makes economic sense. Very few companies grow gangbusters outside the clusters.