Tech tycoon Elon Musk is one of the richest men in the world, and also a pioneer in ultra high-tech industry.
The Forbes list of billionaires ranks him as the 54th richest man in the world, with an estimated fortune of $20.8billion.
The 46-year-old’s rise up the wealth rankings has been rapid, after making his first appearance on the billionaire list just six years ago in 2012, with a fortune of $2billion.
Of course, without access to their bank statements, it’s difficult to say exactly how much cash the rich and privileged have, so publications differ in their guesses about individuals’ worth.
Bloomberg ranks Musk 45th on their Billionaires Index, and estimates his current wealth to be $21.2billion.
How did he make his fortune?
Born in South Africa, Musk went to university in Canada in 1989 and then the US in 1992, where he got involved in the tech industry.
His first company, Zip2, licensed online city guide software to newspapers, and he sold it to Compaq in 1999 for $307 million, aged just 27.
The same year he joined a group of other entrepreneurs to create online bank X.com.
X.com merged with Confinity in 2000, eventually becoming PayPal.
Paypal sold to eBay in 2002 for $1.5billion, with Musk netting $165million from his shares.
What’s he doing with all the money?
Musk invested a huge chunk of his personal fortune in getting his space company SpaceX off the ground.
His idea was to create commercial reusable rockets that offered companies and government agencies an affordable way to put satellites and other cargo into orbit.
His long-term goal is to democratise space and eventually send humans to Mars.
SpaceX suffered several failed launches and was nearly bankrupt, but managed to successfully create and launch the Falcon 1 rocket and earn a contract from NASA that set it on its path to becoming the first commercial company in history to dock a craft with the International Space Station.
At the same time, Musk was helping to fund the growth of electric car startup Tesla Motors that had been formed in 2003. The company suffered in the 2008 financial crash and Musk took over as CEO.
Musk also has interests in SolarCity – specialising in solar power technology – and Hyperloop – a planned 500mph transport tube that could cut travel times from London to Edinburgh to half an hour.
Among his latest ventures is OpenAI – a firm developing artificial intelligence.
Will his kids inherit the wealth?
Musk’s first son with wife Justine Wilson was called Nevada, and tragically died from Sudden Infant Death Syndrome at the age of ten weeks.
The couple went on to have five more boys – twins in 2004 and triplets in 2006. The couple later divorced, but they share custody of the children.
But whether his children will inherit his wealth is another matter.
He has signed up to the Giving Pledge – an initiative launched by Bill and Melinda Gates where the uber-rich agree to give more than half of their wealth away to philanthropic causes.