I have a small setup that could be considered homelab-ish - a NAS, a server, Docker+Portainer running a variety of services including HomeAssistant, a Plex server, UPS with graceful shutdown, and other stuff. I agree it's educational, it certainly has been for me; but everything I run has a practical purpose.

People will build a huge multinode cluster in their basement with Raspberry PIs, and benchmark it to point out performance issues that they absolutely can't live with and so they are off to buy new SSDs or whatever. It's a hobby, but it's shaped like someone's actual job.