In one of the former fediverse hype cycles (either 2020 or 2018...) I made an account on an instance that was not one of the main 5 ones and followed a bunch of people. Some weeks ago I looked at that account and literally 90% of the accounts I had followed had vanished because the instances _they_ were on went offline in the meantime. Honestly a little surprised the one I chose was still offline, as it's also just a random small one.

Yes, this is probably not so likely for mastodon.social or SDF, but still. It's just like getting a free email account at some random place, it could be gone every day.