Between 2005 and 2007, I socked away some serious time in Warcraft. PvP, raiding guild, end game content, officer, the whole 9 yards. Though I still keep involved with my guild to a small degree, I no longer play WoW. Sure, every once in a while I might hop on for a month, but I got out of it what I wanted to. I've had that gaming experience. Would I do it again? No. But I'm glad to have had it.
9 million players can't be wrong.