I agree that self hosting is useful for things that require lots of storage or processing power, but there are more reasons to self host than that. For me, it’s more that I want control of certain services, and that I want a central place to manage them from. For example, I personally host an Immich server on a local rig in my home along with a number of other services that don’t require enormous amounts of storage or processing power.
Home Assistant, Jellyfin and the Arr stack, Audiobookshelf, Koel, Immich, etc. Things like Jellyfin require large amounts of space, sure. But things like the Home Assistant, Arr stack, Audiobookshelf, and Koel are more for convenience than anything else. Going back to the Immich example, this provides me with a way to centralize my family’s photos while on our local network, or a VPN, and allows us to share them publicly with others using explicit links. It keeps our personal photos out of the corporate cloud and provides mostly the same functionality as though I were using an alternative mainstream product. That and if someone yeets my phone into the ocean for some reason, I still have all my photos.
Having explicit control of these services and the underlying content is probably more of a reason to self host than anything else for me. S3-type bucket storage and spot processing power is relatively cheap these days. Privacy and control is not.
I personally use Syncthing for backing up gamesaves to my home server and it works great. While it would technically work for this application, it would be significantly more work to set up and maintain for photo management than just kicking up an Immich Docker container. Go check out their docs if you haven’t already, it’s pretty sweet how easy it is to manage stuff with Immich