Another way to look at it is that I would prefer to focus my limited available time on making 3D models for engines, and printing the patterns for those engines, instead of building 3D printers.
Its a matter of focus and priority.
It is basically whatever you have fun doing, but my end-game focus is to make engine castings and build engines, and let someone else sort out the 3D printer stuff.
- To built a printer to practice debugging, experiment with spareparts, soldering wires to each other, program microcontrollers, try out different sofwares etc. is one hobby.
- To print with different (colour) materials, designs downloaded from the internet, is another hobby.
- To buy a printer to print parts for another hobby, or for work is an entirely different thing again. And there maybe overlapping interests.
Building a "state of the art printer diy" is becoming again more a hobby in itself, because with all the new introduced sensors and firmware settings you need to spent time in order to learn what you are doing.
It was difficult to get the machines running at all in the beginnings, when people made their own heaters with wire and capton tape.
(Google "Mendel 3d printer" to get an Idea what I am talking about)
Now it becomes complicated again if you want to incorporate a lot of the latest features into your DIY machine, you cannot do it without investing time and understanding a little what you are doing.