not really. people who have a lot of gamerscore don't necessarily* have no lives. they just like to complete their games. i got gamefly and my gamerscore exploded. i would get a game do everything possible, and send it back, at first just to get the most out of 10 dollars a month but i eventually started going for all the achievements as a keepsake. i am about 600 away from 20k and rarely play my xbox anymore.
*when i meant a lot i meant like reasonable. 20-30k. anything over that is ridiculous. xD