How free it is depends on the times. In 2000, the dot-com bubble collapsed. This spilled over a little into Fortune 500 companies, but not as much as it affected startups and tech companies. I left my dot-com in New York and went to work at an investment bank. A lot of people I know in the Bay area were in tougher straits - some who had moved there left. Sometimes there are advantages to a city being dependent on one industry, sometimes there are disadvantages.