By the time Elon Musk founded the company that would become PayPal, in 1999, he had already built and sold one internet business. But this time he hit the jackpot. Already wealthier than most of us will ever dream of being, he netted close to $180m from PayPal's sale to eBay, enough to retire at the age of 32, or to set up a venture capital fund and invest in hungry young entrepreneurs such as he once was - the conventional path for made men in California's Silicon Valley.
But this is not what Musk did. Since the birth of the internet in the mid-1990s, there have been complaints that, with the best minds of a generation focused either on finding new ways to play the stock market or on tinkering with software, the big picture was being lost. With so much novelty in the world, who has time to look up and dream of building moon bases or cathedrals?
The answer seems to be Elon Musk. In 2002 he launched SpaceX, a private company focused on shaking up the moribund space industry. Then a year later came Tesla Motors, a start-up car manufacturer that aimed to produce all-electric production cars, something mainstream manufacturers had tried to do and failed miserably. By any rational assessment, both projects were preposterous and doomed to fail, and when their originator voiced an ambition to colonise Mars, even admirers began to mention the word 'hubris' - destroyer of many a rich young net mogul. When Musk's companies hit trouble, he was widely assumed to be through.
No. By the time we meet, Elon Musk sits atop two billion-dollar corporations and appears to stand on the brink of changing the world in significant ways. Tesla's first all-electric family car, the Model S saloon, hit US streets with the highest ratings ever conferred by either the National Highway Traffic Safety Administration or the influential Consumer Reports organisation, and went on to win several significant awards, while SpaceX has been contracted by Nasa to ferry cargo and ultimately people to the International Space Station, effectively replacing the Space Shuttle.
In 2013 he was named business person of the year by Fortune magazine, and later that year in August, the day after Tesla officially moved into profit, Bloomberg estimated his personal wealth at $7.7bn, making him the 162nd richest person in the world at the age of 42. Everything about him is mind boggling.
Married, divorced, married and then divorced again to the British actress Talulah Riley, and with five young sons from his first marriage, Musk leads a life as colourful as the comic books he might have sprung from. So who is this boyish-looking half-man, half-screenwriter's fantasy - and where on earth did he come from?
Needless to say, getting an audience with Elon Musk is akin to rocket science these days. In addition to flying his own jet between the Tesla plant near San Francisco and the LA headquarters of SpaceX, where he oversees a rapidly expanding launch schedule as CEO and chief designer.
Musk occupies a corner workstation near the front entrance. Twice I am given a time to meet him and twice 'urgent business' intervenes. When eventually I am led over, I find him in a white checked shirt, jeans and trainers staring intently at a computer screen.
He is taller and broader than expected from his boyish good looks and geek-god propensities, with the surprise build of a rugby player. I inadvertently make mention of his computer mouse and get a three-minute meditation on the evolution of the mouse as a tool. Still reeling from what I've seen in my first rocket factory, I wonder almost involuntarily whether the scale of what he has done ever scares him, and am surprised to see him relax at the ingenuousness of the question.
'Yes. Yes,' he smiles. 'We started with just me at SpaceX and now it's 3,000 people… It is kind of crazy.'
Musk was born 44 years ago in Pretoria, to a South African electrical engineer and Canadian model mother, Maye Musk. His childhood nickname was 'Genius Boy': he wrote and sold his first video game at age 12, but was bullied at school for being a smarty-pants. No less out of step with the Silicon Valley mainstream, he has clashed with peers including Mark Zuckerberg of Facebook. Often described as a 'disrupter' - the most coveted epithet among libertarian-leaning techies such as Zuckerberg - Musk bridles at the term's application to him.
"A lot of my motivation comes from me personally looking at things that don't work well and feeling a bit sad about how it would manifest in the future. And if that would result in an unhappy future, then it makes me unhappy. And so I want to fix it. That really is the motivation for me. I certainly don't believe in disrupting things for the sake of it.
The year Musk became properly interesting was 2008. Until then, adult life had gone almost embarrassingly to plan. Simultaneous degrees in physics and economics were followed by marriage to the fantasy writer Justine Wilson and the mid-1990 web-rush. With his brother Kimbal he founded Zip2, an online media services company which was sold to Compaq for $307 million in 1999, followed by X.com, which soon became PayPal, bringer of SpaceX and Tesla: so far, so good.
But then in 2008 three failed launches left SpaceX hanging in the balance, just as Tesla's flagship Roadster hit every production problem under the sun. Footage of Musk addressing a crowd of angry Tesla customers still makes me shiver after three viewings and his subsequent admission that, 'That's as close as I've been to a nervous breakdown,' rings uncomfortably true.
Musk's nostrils flare as he contemplates that year, in which any rational observer imagined him finished. He rocks back in his chair and exhales deeply when asked just how close he was to the brink. 'Both Tesla and SpaceX were very close to dying. SpaceX had our third launch failure: we just barely had enough resources to do a fourth, and if that had failed it would have been curtains. Fortunately, it worked, but even then we weren't quite out of the woods.'
I find it hard to believe that he really had nothing squirrelled away.
'No. Everything that I've earned up to today is in this. Eventually we were awarded a big contract from Nasa, but what a lot of people don't understand is that up to that point all the funding had come from me.'
So he really would have been back to square one? 'Yeah, absolutely,' he smiles wearily. 'In fact I would have been slightly worse than square one, since I would have owed money to my ex-wife, among others.'