A friend of mine recently sent me this email and I believe it answers the title of this post perfectly:
I guess it’s a combination of things. Work was taking up more of my time and WOW felt like a second job when just one job was already enough for me. But ultimately it came down to this. If I put in 10 hours pumping out presentations for my boss, reading about mutual funds online, etc. I came out the better for it. However, if I spent the same 10 hours playing, maybe I’d get a level up out of it but when I log off the game, what do I have to show for the last 10 hours of my life. Not much.