Why do people stay in cults

Fear of the leader, or life outside the cult.

Explanation:

Fear of the leader will most likely stop you, because you are in fear of what he / she might do to you. Your life could be in harms way if that leader isn't put to justice, and that can be very terrifying to someone leaving a cult.

Imagine being brainwashed, and apart of something for so long. You wouldn't know how to adjust to the outside world, especially if you know no better. Of course, leaving a cult would probably not lead in death because you cant catch your food, you still wouldn't know how to fend for yourself.

Imagine being a whale in captivity. When you are finally released, you would not know how to hunt for food, and that can lead to death.