I always looked at playing in shops as free geek advertising. When theres 200,000 points worth of models on a table that helps sell the game.
I can see this point, but I'd counter that more people in the hobby benefits me just as well. More variety, more people to meet, more/bigger tournaments, less chance the game goes the way of the dinosaurs, etc. If you're the kind of guy that only plays with your group of pals, then this probably means less to you; but as a "geek," I'm always looking to bolster the geek crowd.