They obviously don't. Look at TF2, they refuse to say it's dead but it hasn't received a proper update in a year. Instead, they spread a gambling model across all their current games and now sit and collect profits. Heck, even those "steam boxes" which were supposed to make PC the "final gaming platform" fell way short. Valve is an e-commerce company with a game development side business now and frankly, their recent output hasn't been good...