Some people leave because of rebellious nonconformity issues.
They live a life of freedom with little self direction from being overtly oppressed being a JWS.
All too often though they get themselves into problems from out of that freedom, eventually seeking some direction once again.
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I've been on this site for more than 6 years now I don't perceive there's a growing increase of people returning to the JW organization.
Really how can anyone measure since they would just simply stop posting.