Cult indoctrination and cognitive dissonance.
As far as those that went to Bethel or became elders, I think many are affected by the big-fish-in-a-small-pond syndrome. In the real world, most would never get the recognition that they get in JWdom. They may not even realize that they crave this recognition, but it serves to cement them into the org. Also, most of those that went to college and university in previous decades did not have access to all the information that kids today have. Now that they are older they are set in their ways and, unless something disturbs them, they will never start questioning, looking outside the org, or using their critical thinking skills on JW doctrine.