Sighs ... the enthusiasm is appreciated, but reacting to the numbers like this without looking into what's going on is likely to lead to false conclusions.
In this case, I'm pretty sure fedidb is making a mistake and reading two separate endpoints of the kbin.social instance as separate instances when they're the same. As kbin.social has ~50k
users, this number is about that much too high. See the servers list for kbin here: https://fedidb.org/software/kbin
I've messaged the admin of fedidb on mastodon about this and so they know. But at the moment it seems the admin is setting something up that looks like separate instances without being so.
See mastodon thread here: https://hachyderm.io/@maegul/110707923404220007