I'm seriously curious about this as well. 300k a year for 5 years would buy at least a decade of time for working on startups for me with no reduction in quality of life... that's a tough sell to beat.

Although... none of the Microsoft people I know seem to be doing significantly better than anyone else I know. Maybe it's a local to Seattle thing, but the MSFT people near me are still driving Hondas to work.