Comment by bluGill

There is a point there: I can buy sheet metal and a welder at home depot and repair rust in a 1950s car (if I was really doing this I'd get better metals and a better welder, but the home depot stuff will work). If the CPU on my modern car breaks I can't fix it - worse, the computer industry has a long track record of stopping production on older chips and so there is a good chance the part I need won't be available at any price. (there are a few labs that can make a one-off chip - but they start at $60,000 each and that assumes you have all the designs ready)