Earlier quoted context omitted.
I think the smartest thing Musk ever did for Tesla was to start sending rockets into space and landing them over and over. It really makes you think, "Hey, if they can do all that rocket science, they can probably make a sedan." (This is mostly a joke... but it's also not entirely a joke)
Rockets may be easier to develop than a product for the mass market. Car manufacturers have had many decades of optimizations of their processes. It’s very hard to catch up.
Can't find it now, but Musk said something like "For a rocket, manufacturing is 10 times harder than building the actual rocket. For cars, it's 100 times harder".
This is not that surprising, the incumbent manufacturers have decades of experience, vast amounts of know how and optimized supply chains. There's a reason why no new manufacturers have emerged.