Lemmy.ca's Main Community

You can run your own instance and not allow anyone else to sign up, though I do agree the effort it requires if it's just for a single person is a lot. Spread out amongst friends, or other folks who don't mind chipping in, makes it seem a bit more sensible. But there is always the option to turn off registrations, and on Lemmy at least you can make registrations require approval.

The only other way your instance could incur more running costs than you'd like is if you have a community on your instance that gets very popular, and folks from all instances start posting to it (think stuff on Beehaw, Lemmy.world, etc.) Then your server needs to be the man in the middle, facilitating communication between users of other communities. But you always have the option of not allowing communities to be created, or stopping federation altogether if it gets to be too much. There really isn't a way it would suddenly cost you more money than you thought, unless you aren't monitoring it enough (which isn't much more than setting up notification emails for storage use, system crashes, etc).

Running your own instance is the only way to really be sure that the costs are being covered on the up-and-up. Otherwise you're just taking folks at their word. Your data, in the end, could always be sold to anyone. It is publically available through the ActivityPub protocol, after all. But that also means there's really no need to pay for it, so no one would buy it.