But third party companies like EA/Activison/Ubi and the First parties themselves sell a LOT more software on consoles than they do on PC, and at higher price points.
Activision can sell 8 million copies of COD:MW2, then turn around the next year and sell another 12 million copies of Black Ops at $59.99 on the 360 alone. EA Can sell 10 million copies of battlefield in a year, AND 10 million copies of Fifa AND 5 million copies of madden- and will probably do it again next year. 12 million copies of Diablo 3 is great, until you realize Microsoft somehow convinced 24 million people to buy Kinect Adventures.
This kind of volume doesn't really happen very often on PC. What else moves that much software annually? The Sims? not for a decade now. Granted, revenue is a lot different for F2P titles and MMO's, but EA/Activision/Ubi/etc tend not to make very many of those- and it's very hard for a company to have more than one successful MMO at one time- or a successful MMO at all, as EA found out the hard way with that Star Wars MMO.