Can 3D printers print with 1 micrometer (not millimeter) accuracy? 1 micron gets you things like the original 8086. Oh wait, current best desktop printers get like 100 micron (0.1 mm) accuracy. So scale up what we have now 100x in terms of accuracy (imagine how much bigger / more precise the motors, magnets, everything has to be). EASILY 10-50x the cost of a good home 3D printer today - say $50K. And 8086? Your phone is faster than probably 50-100 of them in parallel today) - so $100K (materials aren't cheap) to print a series of chips that were insanely obsolete 20 years ago and 1 $500 fpga could run circles around. Then scale that up at least another 50x to get semi-competitive (20 nm). There's a reason they put fabs in places like Arizona where there are relatively few earthquakes... Even the garbage truck driving past your house could damage your chip.

As far as home printing stuff: the clean room requirements are INSANE: just the HF (hydrofluoric acid) is crazy bad stuff that you could NOT get certified for general consumer use, no way, no how. And even if you did, you'd be crazy to buy something that comes with HF as part of the process.. And that's just ONE bad, bad chemical used by TSMC all the time.

FPGAs are the "faster-than-software / can make a custom chip" compromise - companies like Intel used to (not sure if they still do) use a ton of FGPAs to simulate new chip designs. Precisely because manufacturing state-of-the-art chips is so hard.