Part of it is it’s just familiar. I know WoW, I’m comfortable with WoW. Long history. Other MMOs just aren’t options for me anymore, I don’t want to put the effort to learn a brand new one from scratch. If WoW ever shut down I probably wouldn’t do MMOs anymore.
And overall I do like the game! It’s fun, I’ve been a fan of the series since WC3. There’s high times and low times, but not enough to make me quit forever. WoW’s a game I can just keep coming back to as it keeps adding more stuff or I can generally find more things to do. The sheer amount of entertainment this place has brought over the years is more than worth it. 