I don't mine because I don't want to wear my card out for Battlefield 3.
I'm hoping to make enough from Bitcoin to be able to have a dedicated rig with a 6990 ready for when BF3 comes out. The games going to be kickass IMO.
As for not mining, I can't stop - I'm well addicted now.
I'm also using my bitcoins to (slooowly) build up a good gaming rig. I got the case (corsair 800d), and now working towards a 6990 (or two, depending on how well bitcoins do later in the year). I was never in it to profit (plus I didn't get into bitcoins until May). Just for some casual cash to buy computer crap that my wife won't let me buy.
She doesn't see the few extra cents per month in electricity, and also doesn't see any unusual credit card purchases (thanks to newegg gift cards purchased via bitcoins)
I'll admit I should have got the 6990 first before the case (so that I could earn more bitcoins to make this faster)... but my current case can barely keep my 5770s cool, so I needed to get that first.
After 6990s will come some SSDs