There several reasons to continue bad games for me:
1) Money. If I have paid for it, I must end it. Even if it's bad. Even if I'm fed up. I hate wasting money.
2) Reviews. If the game is bad, and that is not only my opinion, my task is to write a review and tell other players what features I don't like.
3) Bugs. Oh, well, the funniest part. Some bugs are really funny, so searching for them is kind of in-game hobby.