I've been a gamer as long as I remember having a computer. I remember being completely consumed by the old game Dinky Doo on the C64 and later by Giana sisters.
I game because I feel like it. Watching TV is good at times but you don't get to have your say in what happens, just sit back and watch which is fine if you're tired. But gaming means you get to be slightly more active without having to go actually excersice. Gaming allows me to have a challenge at completing something while having fun at trying to complete it. There are times when games get a bit too hard for me though at which point I either give up or it becomes an obsession to complete the game.
At any rate. I guess it's all about having something interesting and fun to do to while away the time, to feel that in a world where gravity is a tough negotiator, weather sucks and school is trying you can always relax with a game and know that it won't bore you to death and if it does you can always turn it off. (I want an off switch for one of my teachers once in a while)