I like to tinker with things, and I had hardware lying around I wasn’t using. First thing I ever self-hosted was very basic: a Terraria server.
Then a Minecraft server.
And then a fully featured and defederated Matrix server with a fully functional telegram bridge, mostly as a test to see how feasible it was. Ran it for several months before shutting it down, deciding to wait for dendrite, since it’s supposed to be lighter.
Haven’t done anything since, but I’ll be looking to build a few more things in the near future.
Dendrite is supposed to be lighter on resources than Synapse, but I have no evidence other than dev claims. I had no performance issues when running Synapse a couple years ago.