After dropping out of his PhD program at Stanford, Musk and his brother Kimbal launched a software company in 1995 called Zip2, using $28,000 of their father's money. The Internet was beginning to expand by leaps and bounds, and newspapers were trying to figure out how they could make the best use of the new medium. The Musks’ company developed online city guides for newspaper publishers. Before long, Zip2 had won contracts with major players in the industry, including The New York Times and the Chicago Tribune.
But there was tension at Zip2. Musk wanted to be CEO, but the board stood firm against the move. In 1999, as the tech bubble was approaching its zenith, the board sold the company to Compaq for $307 million plus $34 million in stock options. In the sale, Elon Musk received 7% of the sale, $22 million. (See also: Three Steps Elon Musk Took To Become Successful.)
That same year, Musk co-founded X.com, an online banking company, using $10 million from the sale of Zip2. A year after that, with the dot-com bubble fully popped and a preponderance of tech companies closing their virtual doors, X.com would purchase Confinity, another online financial services firm, and its money-transfer service, called PayPal.
It quickly became clear that PayPal was the most important element of the company. X.com focused on the service and renamed itself PayPal in 2001. It soon became the online-payment system of choice, with a few thousand users multiplying to more than 1 million in a few months. Its fast adoption is credited to a marketing campaign that recruited new customers when they received money through the service.
But boardroom troubles dogged Musk, who was ousted from the CEO’s chair over technical arguments concerning the future architecture of the service. Again, those battles were followed by a sale, this time to eBay. At the time of the sale, one in four eBay transactions were completed using PayPal. This sale was enormous by Internet-company standards in 2002, with $1.5 billion in stock changing hands. Musk received $165 million for his 11.7% stake in PayPal.
Before the PayPal sale had closed, Musk had begun to dream up a miniature experimental greenhouse that he could land on Mars. The greenhouse, which he called "Mars Oasis," would contain crops and would, he hoped, rekindle well-faded public interest in space exploration.