That's what Musk wants to drive down. He has said so explicitly and unambiguously many times. How to bring the cost of launches down? Don't throw the rockets away each time. How to bring the cost of boring down? Increase the speed of the machine (here the multiplicative factor is time, reduce time, reduce cost, ergo increase speed.) How to not throw away rockets each time, reuse them by making them land without damaging them.
I'm not sure he "makes tunnels the way you make spaceships". These are the similarities.
(1) Search for a social problem: lack of cheap access to space, traffic congestion, fossil-fuel propulsion
(2) Figure out what the factor limiting progess: rocket reuse, 3-d traffic network, battery tech for EVs
(3) Focus all your energy on that problem: figure out how to land a rocket, figure out how to bore tunnels for a fraction of the price, build a gargantuan factory optimised to drive down the cost of battery production
Look folks. There's no magic formula here. It's not rocket science. (Except in one case). I'd say what is common to all three ventures is Musk's personality. Tackling enormous problems. Getting to the heart of the problem. Self-belief. Drive. Focus. Tenacity. Bravery. Great engineering skills. Surround yourself with talented people who get shit done and have the same optimism as you. Wash, rinse repeat. What the biotech community need to be figuring out is not how to clone monkeys, but how to clone Musk.
hagiography over :)