The thing is, the cost of making them at home is both laborious, poorly reproducible, and lower quality than getting it done at JLPCB. In the old days, it was done with an exacto and rubylith. Today it requires a laser setup for about $4000 and you still need to manually apply and remove a resin layer. It's mostly not worth it to do things this way, and you lose the ability to have more than 2 layers in your board.

The bigger issue with PCBs is that even with a nice prototype, actual manufacturing needs to be done in Shenzen for any sort of cost competitiveness if you want to step outside of the hobby realm (just as the author of this essay stated).

It's really, really hard to see where the USA stands in the value chain any more once LLMs have been deployed. If all the physical manufacturing lives in China, where the manufacturing supply chain also lives, and Chinese AI companies can very very easily distill US LLM models, the two remaining US advantages is actually just the dollar's role as reserve currency --- something that crypto bros and the US president is working on eroding at a record pace, and the fact that this overvalued dollar gets all the smart people in China and India to emigrate to the US -- also becoming politically less viable.