Nobody else did, though.

That's the reason he was able to get this rich with SpaceX and not stall sooner — most of the other space companies were (and in the west, still are) busy scratching backs rather than developing successful products.

Someone like Boeing. The administrative class has taken over and they have zero risk appetite. Nothing new will come of them.

You honestly believe that DARPA would have given us the Tesla model Y?

DARPA doesn't give us anything, it just runs with ideas and develops them enough to push to others to build and run.

ARPA gave us TCP/IP, but MS, Google, telcos, etc. gave us the modern internet and the tools to use it

It's possible that Tesla, which Musk didn't found, would have given us an EV by another name. Rivan also got us an electric truck before the cybertruck came out. Fisker's not doing so well though.

Possible sure - just as it is possible my next startup could be the next Tesla. In reality, when Elon joined Tesla they had nothing but early concept prototypes of a high-end sports car with the name Roadster. Elon took it from concept, to launch, to production. Then he did the same with the Model S/X/3, sold 5 million electric vehicles, made them so compelling that it completely disrupted the ICE vehicle market and sparked a gold rush of elecrification in the car industry resulting in a Trillion-dollar company.

It's possible "which Musk didn't found" is doing some heavy lifting in your statement above.