Oh and one other thing. If the people you point at mastodon.social are the type of people who are reasonably well off, maybe also suggest the "If it's useful to you, give the people running the servers a bit of money to help with their costs" is a good way to help explain how this sort of thing can work in practice ... It'll be fine to pay less than your mobile, music or Netflix subscription ...
It's up to us, the users, to push it if we want to make this a ubiquitous system ...