The numbers for lemmy are probably way outdated. Take a look at https://lemmyverse.net/communities. It lists 636 instances but FediDB only has 302. And remember most of this growth has only come in the past week or two.
Also, mastodon only has 1.25 million active users according to FediDB, though that's probably outdated too.
I've never really understood the EEE argument here. XMPP was an open proptocol, Google embraced it and attracted users, then extended it and took those users away. But according to this article, Google didn't extinguish XMPP. It's still around and serving its niche community.
That's already the situation the fediverse is in. This is a niche community and there are already existing social media companies that the majority of internet users are on. If Facebook joins the fediverse, it brings billions of new users to the fediverse. If they then leave the fediverse, ActivityPub will still be here and all of us on the real fediverse will still be here, in a niche community. Everyone here has already chosen the fediverse despite it being a clunky, unpolished, niche network. How is EEE a relevant fear for the fediverse?