Dorothy Thompson, back in August of 1941, published an article in Harper’s discussing the susceptibility of various types of person to succumbing to the influence of fashion, of conformity, of opportunism, and to the appeal of the mass movement.
It is an interesting and somewhat macabre parlor game to play at a large gathering of oneâ€™s acquaintances: to speculate who in a showdown would go Nazi. By now, I think I know. I have gone through the experience many timesâ€”in Germany, in Austria, and in France. I have come to know the types: the born Nazis, the Nazis whom democracy itself has created, the certain-to-be fellow-travelers. And I also know those who never, under any conceivable circumstances, would become Nazis.
Wikipedia article on Dorothy Thompson.
Those of us in the Baby Boom generation who lived through the time of the Anti-Vietnam War Movement saw plenty of the kinds of joiners Dorothy Thompson describes.
Hat tip to Karen L. Myers.