Never ask a man his pay, a woman her weight/age, or a data horder the contents of their stash.
Jk. Mostly.
I have a similar-ish set up to @Davel23 , I have a couple of cool use cases.
I seed the last 5 arch and opensuse (a few different flavors) ISOs at all times
I run an ArchiveTeam warrior for archive.org
I scan nontrivial mail (the paper kind) and store it in docspell for later OCR searches, tax purposes etc.
I help keep Sci-Mag healthy
I host several services for de-googling, including Nextcloud, Blocky, Immich, and Searxng
I run Navidrome, that has mostly (and hopefully will soon completely) replace Spotify for my family.
I run Plex (hoping to move to Jellyfin sometime, but there's inertial resistance to that) that has completely replaced Disney streaming, Netflix streaming, etc for me and my extended family.
I host backups for my family and close friends with an S3 and WebDAV backup target
I run Frigate on a few PoE cameras in the forest behind my house to check out wildlife
I use the audio streams from my cameras to check for birdsong, identify birds, and archive and submit the detections to a citizen science website (https://app.birdweather.com)
I run 4x14TB, 2x8TB, 2x4TB, all from serverpartsdeals, in a ZFS RAID10 with two 1TB cache dives, so half of the spinning rust usable at ~35TiB, and right now I'm at 62% utilization. I usually expand at about 85%