Jehovah's Witnesses have hope
Hope is useless. I can hope to win a lottery and it won't make it happen. I can hope in a toothfairy and it won't make it real. JW hoping in paradise is no different than hoping to win a lotto as it's an idea sponsored by those at the top which is a bit more colorful than the lotto corporations put in their ads.
As for the original question, I'm guessing there are many answers but the vast majority who stay don't have a clue about wts' past thus they are believing the shit that is printed and forced on them every meeting they attend which controls their thinking habits and their behavior. I would never left, have I not found old wts publications which opened my eyes to the wts deception. The problem is that some of those that leave wts without learning the truth about wts are affected by the wts doctrine which leads some to return to the cult years later and others live a "defective" live styles believing that they left God's organization and will ultimately die soon at armageddon.