The cult instills self-doubt in people. They repeatedly stress scriptures like Jeremiah 17:9 (the heart is treacherous, who can know it) that cultivate a fear of trusting oneself. Combine that with an encouragement of what is presented as rational ignorance (i.e. why waste time reading apostate literature when you know it's filled with lies? It's not worth the effort) and you've got a pretty powerful thing going - a fear that you're not strong enough to resist being misled (or, in my case, that your motivations for research are actually selfish so you'll inevitably find things wrong with the cult as a way of justifying a desire not to put in the work) and a rationalization for why you're smart not to research. Then there's also a desire to avoid indulging those evil apostates by reading anything they write. Those three things are what held me back, at least.
As far as actual biblical research - I was never afraid of that. I just didn't care and couldn't be bothered. I wasn't interested in the bible at all, and I had more than I wanted of the bible's nonsense force fed to me several times a week for my entire life. And in the bits that were forced on me I already saw problems that took a lot of effort to rationalize. Because, after all, my heart was treacherous - I told myself this was a failing on my part - I just didn't understand and couldn't no matter how hard I tried. So why would I want to do more research into the bible when I'd just come across more problems (that I now know are actual faults of the bible) that would only demonstrate to me the extent of my lack of understanding?