You're self hosting: no qualms with that.

The most populous server is mostly full of people freeloading. They're the same types who torrent without seeding.

It's usually not that big a deal as long as the server has some people chipping in for upkeep but no matter how you slice it: if your account is on a server you're either contributing to upkeep or leeching off the donations of others.

Self hosters arent leeching: they're participating in the decentralization.

With federation servers cache content from each other and then serve it to their users. If you have a ton of users you're using a ton of bandwidth. Simple as.