My parents became JWs in the late 50's and during these years there was a lot of political unrest. There was also the cold war between the US and USSR. I remember listening the the news on our old black and white TV being scared that the end was near. I am sure this was one of the motivators for my parents to join. Also, my mom had just lost her dad and because he hated the Catholic church he didn't want a religious funeral service. Because my mom and her older sister had started studying with the JW, their whole family blamed them for "corrupting" their father's mind. Of course, at the viewing the funeral parlour was full of JWs - love bombing played a major role in my mom's conversion and she didn't have to make peace with her whole family now that she had all these new brothers and sisters to support her. Then a few years later, her older sister and her husband and children suddenly left the "truth" with no explanation...mom never questionned why and we shunned them completely. My mom never had a relationship with her very large family and we grew up knowing just a few amongst dozens of cousins.
Things haven't changed much today...some become witnesses because they think our world is threatened and something is about to happen and others find comfort within the congregation which fills a void in their life....