I started out with the MUDs, did some DAoC, CoH, WAR, etc, but I've stuck with WoW. I started WoW about 4-5 months after launch. I've taken a 6 month break from it, but I keep coming back to it. I enjoy both the PvP and PvE aspects of the game and find the new content they keep releasing refreshing. Also the game has been updated again and again. With the launch of Cataclysm the talent trees are being made smaller. You'll be able to fly in the old world, etc. For me it's more of a social thing than a game. It's my Facebook, MySpace, Twitter, whatever you want to call it. It's where I spend my time talking with friends and doing an activity. Also the cost per hour is minimial. Even if you pay 15/mo in the US, it still works out to a few cents per hour (I play alot in a month). Even if you play for 2 hours a month it's cheaper than going to a movie.

Well doesn't it depend on which path they take to work.

Obligatory XKCD reference!

http://www.xkcd.com/85/