I think it might be a bit of an xy problem. I myself have hoped for the runaway success of the fediverse. But I realized it's not actually some absolute number of users I want. What I want is for the fediverse to have that same "there's a community for anything" that reddit had.
I'm starting to hope the fediverse doesn't get too big now, honestly. There's a certain number of eyeballs that is going to attract people interested in exploiting those eyeballs, and I don't know if the fediverse is robust enough to fight them off as the pot of gold they see begins to overflow. It's hard balance to find. And maybe the decentralized aspect of the fediverse does mean that it can't be fully assimilated by capital, I don't know.
Were living in interesting times.