User blog comment:LondonDauntlessCorvair963/CoD in a Nutshell: A Story/@comment-24772962-20150531063206/@comment-25625534-20150531220412

valve's milking it other ways than yearly releases. namely the mann co store and the market. only reason they haven't made more dedicated paid features is because the tf2 team consists of probably <5 people. but hey, they only need <5 to choose which two-dozen hats from the workshop will be labeled "content" and implemented in the new "major content" update, along with three new crate series and, if we're super lucky, an ugly all-class stock melee reskin.

this is all the profit valve needs from tf2. they get enough from dota 2 and cs:go, as well as every single transaction that goes on on steam (they take a cut from almost everything you do.) they're just lucky steam's set them up for all eternity.