It's probably worth pointing out that many people who followed Trump on Twitter weren't fans of his, but people who wanted to keep up with what he was saying (perhaps as critics, journalists, etc) and already had a Twitter account for other purposes. The folks who folowed him to his own Twitter clone were (by and large) actual fans who suppported him.

If you dislike Trump but want to monitor his actions, following him on Twitter might make sense. Joining a platform dominated by Trump supporters probably wouldn't.