A few years ago when I was a JW, I asked an Elder why he had become a JW. Now this guy was a barrister (lawyer) so he not some idiot.
He replied because being a JW meant that he did not have to think about what to believe. It was all set out for him by the Watchtower organisation. All he had to do is go along with what was being taught. If it was wrong it was not his fault, and that it would be corrected at some future date.
It was the way he said this in all seriousness, that got me. That his "eternal life" depended not on his own personal conviction and belief, but on somebody 3,000 miles away deciding what was right or wrong to believe.