Why leave Google to join Facebook?

Someone correct me if I'm wrong but I thought the number of owners that a privately-held company can have before being forced to go public is only 300.

I think Facebook has passed that hurdle. Its users are invested enough by now, with their friends lists/groups/games/etc, that they won't be moving en-masse somewhere else for the foreseeable future.

Even if some new upstart creates a compelling feature that threatens to steal users, Facebook can buy it or copy it, as they're doing with location-based services.

I think people are more likely to switch search engines, from Google to DDG/Blekko/whatever, than from Facebook to some other social network.

Most people change jobs because they want a new challenge. They want to build something new, or do something they haven't done before. The fact that stock options are part of the deal is frosting on the cake.

In the case of high profile startups with multi-billion dollar private valuations, the upside potential at IPO may be pretty limited anyway. Stock options are always a gamble. In this environment of limited IPOs they are a big question mark.

In this case, Google wasn't responsible for Wave's failure to gain traction. Not to mention, Google keeps their employees quite happy AFAIK. I'm sure Wave's death played a key role in the switch, but honestly, that's of no fault to Google.

Imo, it's bad PR for Lars, not Google. It shows he follows the money, or at the very least, allowed his ego to define him.