I know for me, and it may have been the same for you, being a witness was such a chore. I mean, i used to genuinely believe it but i hated the door to door ministry and i could tell people just pretended they had joy in it. One on one many would confess to disliking it. There was always one elder in every hall that was very pushy with the ministry and on a Sunday after the meeting would ask if you're going out. So you would just because you didn't want to say no.
Lifesaving work? Na, it didnt feel like it. I felt like i was annoying people and i felt i looked like an idiot talking about the end of the world.
Then there was the meetings. The obligation to attend all of them. Any hobby you had or anything cool going on always happened to be on meeting day. Thursday and Sundays (and before the changes came in Tuesdays too) had a grey cloud over them because you knew your morning or everning will be wasted on a meeting you're not even interested in. I envied other religions that allowed you to worship in your own home, in your own time and in your own way. Meetings and ministry sucked the joy out of being a JW.
And dont even get me started on the changes in doctrine. I was very studious. But was always discouraged from researching outside the Watchtower. Also discouraged from reading anything by Rutherford or Russell. I went through a time of reading Rutherfords books from the congregation library and was approached by two elders asking why i wanted to read them... very strange.
So in a nutshell, apathy, boredom, frustration, and the internet are bleeding the Watchtower of members and long may it continue.