A combination of historical factors (the concentration of major tech companies here, the resultant concentration of venture capital, even the very idea of "Sili

A combination of historical factors (the concentration of major tech companies here, the resultant concentration of venture capital, even the very idea of "Silicon Valley"), the presence of large feeder populations (Berkeley, Stanford, etc.), a generally high quality of life, and so forth -- there are legitimate reasons why so many tech companies, and so many tech workers, want to be in the Bay Area.