About half the people at Valve have run their own companies, so they always have the option not just to take a job at another game company, but to go start their own company. The question you always have to answer is, 'How are we making these people more valuable than they would be elsewhere?'
The big problem that is holding back Linux is games. People don't realize how critical games are in driving consumer purchasing behavior. We want to make it as easy as possible for the 2,500 games on Steam to run on Linux as well.
If I buy a game on Steam and I'm running it on Windows, I can go to one of the Steam machines and already have the game. So you benefit as a developer; you benefit as a consumer in having the PC experience extended in the living room.