I've always thought that his ideas like the boring company and the hyperloop make a lot more sense when you remember that he spends a lot of time wondering how

I've always thought that his ideas like the boring company and the hyperloop make a lot more sense when you remember that he spends a lot of time wondering how someone should build a moon base or Mars base If you don't have an atmosphere, the near vacuum conditions are free You need robots to dig tunnels if you want sizeable bases. Figuring that out on earth just gives you a headstart. What should transit look like on the moon? On Mars? Can you use those tunnels? What will be different with lower gravity? This is the most charitable interpretation I can make, fwiw