I think, like most cults, it fed on the weaknesses of individual people. People who had problems that they felt could be resolved by giving up their personal freedom to become a part of something that could presumably make them whole again. Even those who just joined because it looked good on their college applications or whatever still inevitably ended up becoming Controllers, unless they decided to leave before it was too late. Sad thing is there are plenty of people who would join something like that, being fed empty promises and vague ideas about becoming part of something. Now, if I knew it had to do with
aliens I might be tempted, myself...
But, yeah. I think it probably gathered most of the hosts the Yeerks had on Earth. I always wondered, did Sharing chapters start to form in random, underdeveloped countries, like I dunno, places in rural Africa or the Middle East? I also wonder if some groups of people, like maybe other real human cult groups, would expell the idea of the Sharing--or embrace it, making it an easier infestation process?