It depends largely on the projects that you choose and your interests. I designed a bolt on venturi attachment to use natural gas with our home generator. I have to admit that I went through quite a few prototypes before I was completely satisfied with my project, but it now works better and more efficiently than any commercially available product.
I have printed out plenty of thingiverse items many of which have not been very useful. They typically cost pennies to print out. I would remind you that a $20 1 KG roll of filament typically goes a long, long way. The nozzles for mine are very inexpensive, typically less than a dollar and last a long time. I replaced the adhesion plate with a piece of glass years ago for about $10. I understand that you have spent quite a bit on parts; I have not spent that much, but even if I had... it has definitely been one of my less expensive hobbies and has saved me quite a bit for specialty parts that I have made for drones, photography, cycling and other activities that I engage in.
Lot’s of cool stuff. The ones I use most are the key hook/shelf. Bathroom holder (fits my toothbrush, toothpaste, shaver, aftershave, floss and flonase all neatly). Have gone through over 20 spools. Never designed anything, just modified things. Did a whole glow in the dark spool a few months back...once again mostly junk toys and jewelry, a spider and some Halloween ghosts. Tried the wood one but that was a failure.