I don't mean this very assertively, just an idea.
Is it maybe easier for a "Born-in" to get out? We "Born-ins" never made a real choice, this can build the deep sense of resentment and entrapment that can fuel the effort to "GET OUT". Persons who came in intentionally obviously either "believed" or found "something better" than being worldish as they had already experienced. I never so much "valued" being JW, it was always a limiting force on me. Yeah the brainwashing phenomena had its grips in me, but that's more a psychological tick than some state of being that I look back fondly about after its lost.
My money is that family pressures/people around you in your life are the definitive conclusion about "how hard" it is to leave. Emotional blackmail and coercion are the real evils here, people believe and fail to believe stuff about god everyday without an excessive amount of drama. The drama comes from how many claws the cult has in you, not so much when it drove the claws in.