Musk co-founded (with his brother) Zip2 in 1995, providing city guides for newspapers. The going was rough at first and the founders had to work long hours and sleep at the office (the horror!) to save money. They sold it in 1999 with Musk getting $22 million of the $305M sale for himself.

Musk used his Zip2 profits to co-found a prototype online banking company he called X.com in 1999. (Yes, you read that right.) X.com merged with Confinity in 2000, and the merged company was briefly called X.com before rebranding after Confinity's killer product, PayPal.

In 2002 eBay bought PayPal for $1.5 billion, and Musk's share of that is how he bought into Tesla and SpaceX.

It appears that those long hours at Zip2 30 years ago represented the last actual work Elon Musk ever did.