It's not the 15.00/mo. It's the time, pc upgrade (in my case - not that the older one wouldn't play it, it was just slowly failing), etc. Sometimes it's even the waning motivation (which is different from support for the game and community). I find myself wanting to play but sometimes too tired to jump though the hoops to get there (and I admit, there ain't that many hoops).
I'm just 'old' and tired.