A lot of folks' fear is that when Mastodon grows it'll absorb bad people. I'm gonna say this. I think even if Mastodon literally grows to the size of current Twitter, the world will be better off overall just because of how Mastodon is structured and what values it represents and what tools it provides for dealing with those problems.
If they don't charge for it? I don't know.
I personally wouldn't mind paying a few dollars a month to use a good Mastodon instance, but it would be a really hard sell for people who expect social media to be free (in other words, almost everyone)
Linux Geeks doing what Linux Geeks do..