Lets face it, when we were in the cult we were told we wernt good enough, not worthy of God the way we are, unacceptable, unclean, "dust"... and that's when we're doing all we can in the cult! So i think those who still feel it is the truth may think that if they leave they're even worse than useless. Which simply isnt true.
Couple this with the shunning and you have a very dangerous situation.
Im not bothered about being shunned, but if my daughter were to die i know i'd want to kill myself. Watchtower takes away everything that should be sacred to you, your self worth, your opinions and even your family. Once you're stripped off all those things you're an empty shell. Which is why it's very important to speak to others, especially ex-JWs and/or a mental health professional.