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.
It’s not like I make or save a lot of money from it, but as a hobby it’s been amazingly fun. Getting into basic 3D modeling has been really cool too, nothing quite hits like making something entirely unique and designed for a specific purpose, then watching your printer just crank it out in a day or two and your imagined thing is all the sudden real.
I’m sure other hobbies can do that too, but for me it was a really awesome feeling :)