People were worried when Mastodon went from 20,000 to 500,000 people too. I don't see why you would think 1mil -> 2mil to be any different. I really don't agree with the comments that suggest that Mastodon shouldn't grow.
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)
This page describes the mastodon.social instance - wondering what Mastodon is? Check out joinmastodon.org instead! In essence, Mastodon is a decentralized, open source social network. This is just one part of the network, run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!
Hero image by @b_cavello