He developed the software for his first company, zip2. Enough to get the POC off the ground and attract investors and hire additional developers to clean up the code, sell it off, build up X.com, sell it off, and fund SpaceX.

No matter how skilled you think he is at it, he is by definition a self taught software developer, who then learned rocket science through the people around him and his employees. People seem to think spending 20 years around literal rocket scientists who are building things for him doesn't cover what you'd learn in 4 years of university.

People dont seem to realize SpaceX is also a software company.