I was thinking about this question today as someone used our work printer for some personal stuff.
As for me, I am printing little things that I would say make it worth it. I’ve printed lens adapters for my camera for example. That’s worth a good 14 to 30 bucks per print. My most favorite photo was with an adapted lens that came from a projector. I also printed IEMs and those things are worth it. Listening to music is second to none on those things. Plus I printed the same shell but for ear protection and again the fit is perfect and sure there’s post processing to get smooth surfaces but in the end it looks like a professional made it. So I think 3d printers are worth it.
For the first 3 years I had fun designing things in CAD. I fixed up or enhanced loads of the things around the house, designed some doodads and widgets, and published the ones that I though other people might have use for. And I had fun earning Prusa meters, participating in forums, and all that kind of stuff.
Then one day, I just ran out of things to fix and inspiration for new doohickeys. That was about a year ago. I tried to print a replacement keyboard foot a week ago and found my printers not working anymore. I haven’t found the motivation to do anything about it yet.