I've been jokingly calling Mastodon "Nicorette for Twitter". It looks and feels like Twitter except it's designed to be unengaging and not very interesting so within a few months most users fall off and stop using it.

It's a social media cessation tool.

@searls Or it depends how many of the Twitter people you'd followed or where they followed you also switched to Mastodon. Starting from zero isn't very motivating, but everyone started with no followers at one time.
@SenseException @searls He's at 3K followers at this point. If he needs more than that, that's a problem with the platform.
@codefolio @searls Not the number itself, but the people who always make you come back to the social media platform of choice.