Comment by ryanwaggoner

I think he's motivated by the idea of building systems that enable other systems that wouldn't be possible otherwise.

Examples would be the gigafactory, his comments about how Tesla is not learning how to build cars, but learning how to build car factories, etc. The approach with SpaceX wasn't "OK, let's build a rocket system that can get to Mars." Instead it was "OK, let's build a company that has a repeatable and sustainable launch business that can drive down cost and drive up efficiency over time, so that getting to Mars won't be a near-impossible problem anymore."

Building a one-off public transit system in the Bay Area, with all the current technological, regulatory, and social headaches, doesn't really offer many opportunities to improve things, does it? Elon isn't God; he can't magically overcome all the factors that cause the Bay Area to have bad transit today, just like he couldn't magically start colonizing Mars in 2004.

So building a new class of technologies to bore tunnels much more quickly, safely, and cheaply seems like it enables a whole new set of opportunities to make the current transit problems more tractable. It creates a whole new set of opportunities for transportation that simply don't exist today.

I'm tired, so forgive me if that isn't clear, just what's running through my head.