I’m not sure they’re all true believers. They may have a sense of belief, but they cannot be true hardcore believers like some people in congregations are. Once you get to those levels of the org (anyone appointed to RBC/circuit or other multi-congregation work can attest to this) there are a ton of things you have to see through that no sane person could honestly accept if they are true God-fearing Christians. The financial accounting only should have people understand the amount of grift that goes on.
I think that most GB members and their staff know it’s a big lie, even if they believe in the core tenets. The problem in any dictatorship is the people around you. There ARE people that will claim to be true believers and happily stab each other in the back just for the power, if not the money. That may be what happened to the last reject of the GB, he grew a conscience stronger than his drinking habits.
Watch “The Death of Stalin” which is historically very accurate, the fact the series of events depicted is what actually happened in real life turns the entire thing a dark comedy. You have to see what I mean, but that IS no different than the GB and JW leadership, I think that is what happened to Morris, he was spiritually (perhaps literally) laying in his own piss dying, people around him were too afraid to do anything constructive to not offend anyone with power while those closest to the top immediately started scheming for the looming power void.
Once you get to Bethel, you lose everything, you lose your family, your job, your support system. You “leave” and are instantly homeless with no skills to speak of.