Yeah he got rejected by Netscape. Also not sure if it was an 'all-eggs-in-one-basket' situation, or if it was the only place he wanted to work at the time. Then the X.com story
Not to contradict Elon, but: I worked at Netscape and did not have a "formal CS background" nor did I ever ask interview candidates about their formal background. recall we hired a guy who's previous job was mixing a Nine inch Nails album. Fantastic coder..
In my experience the whole "must have formal background" began with Google, some years later.