Since I left Yahoo! in 2001 there have been waves of people who have left and then there were single exits. I loved it while I was at Yahoo! It was an exciting time, like the wild west, where we were launching stuff out the door left and right. Much of it was crap (designed by yours truly). Some of it was ok, a few were gold. But I learned a ton and worked with lots of completely different product groups. As Yahoo! grew and grew I felt like it was becoming more of a traditional media company in one respect - it's become a comfortable gig.
There's nothing wrong with being comfortable. If a company is paying you well and you got lots of options and you're vesting, and/or you can work from home once or twice a week, still have the great bennies, vest, etc etc. - it pays to stay (golden handcuffs and all.) Again, nothing wrong with that. It's a good gig, a comfortable one.
Everybody has a risk vs. reward meter especially when it comes to making professional career choices. How highly does an employee value the comfort of consistency?
How does that affect the culture of a company?