The reason most people (imo) keep watching something they have started disliking is because/despite/thanks to the hope of it going back to its former glory.
Lost is one such example of a show which went completely off its bonkers after the first season. The second season was still special and introduced some very interesting characters, but the story development went not just off the rails but way off the planetary scope for railways.
People kept watching hoping to figure out everything and having a way to make sense of it all. All in vain unfortunately.
The Walking Dead had a certain charm to it with the right doses of excitement, story development, drama, romance …. all in one. The acting was quite good and realistic within the setting.
Unfortunately it all developed into a slow drivel with nothing happening (imo).
Since I have quite a lot of other shows I can watch, I have decided to stop shows that lose their interest to me (sooner rather than later), which is why I stopped watching the Walking Dead and Covert Affairs after the first couple of seasons…
End of my two pennies ramble