Seems like one could easily become addicted to using a 3D printer. I just spent an hour looking at… things to print… on one of those sites you linked. When I started looking at the printers mentioned in the thread, they are surprisingly affordable. I can see having shelves full of printable material ( aka 3D ink ) after a year of designing and printing. Then I would want a 3D scanner, which also seem to be affordable, then I would want a designated space to do all this work.
But that all seems normal for anyone that keeps a squarebody in their garage.