I've clocked about 2400 hours in CS:S, not bad for a game I got for free with HL2.
Just as a comment on the game industry, it's actually a little unhealthy to have some games - mostly MMO's but also CS here - that take up such huge time, displacing other games. That prevents the development and sale of other games if people had more gaming time for them.
Other industries don't seem to have the same problem. TV, moview, music have some that get more replayed than others, but none threaten to displace others the way like games.
There's no movie - not even Star Wars - that gets played 2400 hours much preventing the person from buying other movies.
It's ''healthier' for the industry to have games have a more moderate length of play.
I think a lot of people slash their game buying drastically when they find a game that takes up that kind of time. Not sure there's much that can be done about it, though.
The closest thinng is turning those 2400 into a recurring expense - whether a subscription or expansions or in-game currency - but that sill only funds the one game.