I like to compare the fediverse with the forums, TeamSpeak server, and nowaday discord server. It is not suppose to be a huge service with everybody on it a la Facebook, but rather a lot of small community that can interconnect to each other :) .
Everybody use to run a PhpBB or alternative for their own community. I remember being part of multiple of them in the early 2010. A lot of them got replaced by subreddit or facebook page, and this is what the fediverse can replace. Not the whole of reddit or Facebook, but if you want a place for you and your friends to organize your dnd party, run your minecraft server, talk about passion X or Y, the fediverse can do that :) .
When it is useful to even just one person, it is useful.
Open Source doesn't need 'masses' in order to 'be successful. A lot of people make the mistake of applying generic economics to Open Source and related communities.
A federated mastodon or Lemmy instance is successful the moment one or more people use and enjoy it, nothing more. It does not need to have huge audiences to advertise to. It does not need to have Big Data to mine and sell. It doesn't need to pay employees, offices and bonuses. All it needs is one person enjoying it. Or two people having a meaningful interaction, to be successful .
