Education encourages learning. But a bigger factor is independent thinking. For instance, did someone just go to college with the single goal of attaining a job? Was it mainly just business classes, technical classes and the essentials (math, english, etc.)? Or did they also take philosophy, logic or other classes that encouraged them to be critical and question things?
Also, I find with those who leave or resist witness indoctrination, it seems more of a matter of temperament than formal education. Those that resist tend to be independent types who question authority and don't conform easily. A little healthy rebellion never hurt.
As far as financially stable, from my experience that never mattered much. Sure, many JWS are lower middle class to poverty level. But like most here I've known quite a few that are very wealthy. And I never found financial status a reliable measure of intelligence or emotional well being.
I also agree with the posts above that many people join during difficult times in their lives.