I believe that many witnesses are tired out or at least tiring out. I know....... because I am tired out!
Imagine going to college for 20 years not knowing when college is finished. Constantly studying the same stuff over and over in the same boring way. Getting no thanks for all your efforts.
Couple that with the age of the internet and all the negative exposure Watchtower is receiving ....enough said.
Though faith is important. Many need their faith. The repressive rules, teachings and routines of the watchtower society sets people up to fail. . Gradually over the years many simply tire out; or in some cases when individuals find they can't jump high enough, they give up.