I've often wondered the same thing, but couldn't bring myself to put it so bluntly, to an ex-JW. As a few members of my extended family got involved with the JWs, in the early 90s, I never became drawn to it. For me, it came down to always having a skeptical mind, thanks in part to my dad & brother. They turned me on to books by Tom Wolfe, Kurt Vonnegut and George Orwell, while in my teens. In college, I ran across the book, "The Four Major Cults," by Hoekema. That led me down the path to discover the 1975 debacle, Russell's obsession with pyramids, and Rutherford's booze intake and his authoritarian style. This all spelled CULT to me, in huge neon, capital letters, before the internet even existed. Had I NOT had an upbringing which encouraged critical thinking & the questioning of authority (when appropriate), and had I NOT gone to college, would I have been more susceptible to joining a group such as the JWs? I dunno. But, I could see how a lack of such an upbringing could make one more vuberable, I suppose. That's especially so for the ones 'born-in' to the cult.
I wasted alot of breath in the 90s, trying to convince some in my family as to the history of their organization. All the flip-flops, the failed prophecies, the fall of Babylon date, and the encyopedia references which were taken completely out-of-context, and flat-out LIED about in their publications. I even pointed out contradictions in their OWN fucking MAGAZINES, and they still DIDN'T SEE ANYTHING WRONG!! It drove me nucking futs to say the least. To this day, I don't fully understand how a mind can go into 'lock down' mode like that. Steven Hassan's books have shed some light for me, but I guess I'll never fully understand what it's like, since I've never actually 'been there' myself. I try to understand, and my hat goes off to those who do manage to wake-up and find they've been duped. I don't know how I'd feel...probably a mix of sadness and anger, but eventually a sense of pride in finding my own way in life. It'd be a tough pill to swallow, for sure.
I think that many who never became JWs, and stayed 'on the outside, looking in,' probably have the same "WTF were you THINKING," response as Edward Gentry. Again, personal circumstances, upbringing & family involvement in the religion are key factors, IMO.