It’s no secret that Elon Musk is a successful businessman. His multiple businesses including Tesla and SpaceX distinguished him as a leader in the electric car and private space exploration industries.

He started SpaceX in 2002 and Tesla a year later, his third and fourth business ventures. SpaceX gained recognition in 2012 after it launched a rocket to the International Space Station with 1,000 pounds of cargo. The launch was part of a contract SpaceX has with NASA. One the company has continued. SpaceX regularly conducts launches for NASA.

Read: 8 Photos That Show What SpaceX And Elon Musk Think Traveling To Mars Will Look Like

In addition to the major successes of SpaceX, one of his other ventures, Tesla has evolved from an electric car company with one product to a company with three vehicles and more in the works in addition to a solar roof and energy storage venture. The company is also planning on bringing fully electric cars to the mass market. Tesla went public in 2010. Since then, it’s had its ups and downs on the market but overall has seen a value increase. In June, shares broke the $300 mark and have continued to set highs, peaking above $375/share.

As Tesla’s stock soars, so does Musk’s net worth. Forbes estimates his net worth is about $17.4 billion and rising. In the last three months alone, his net worth has increased by nearly $3 billion, Forbes reported, and nearly $6 billion since October.

Musk said last year at the International Astronautical Congress the only reason he was accumulating so much wealth was to one day fund a trip to Mars. He said the only way for the human species to survive a mass extinction event is to become a multiplanet species.

Read: Mission To Mars: Will NASA Or SpaceX And Elon Musk Get There First?

"I really don't have any other motivation for personally accumulating assets, except to be able to make the biggest contribution I can to making [humans] multiplanetary," he said during a presentation detailing his plans to send humans to Mars.

But even all of his wealth is not enough to pay for the cost of a trip to Mars. He estimates it will cost about $10 billion a person. This is part of the reason SpaceX has been working so hard to create reusable rockets and has been working with NASA. The plan is to improve the cost through full reusability, refilling the rockets in orbit, working out a way to create rocket propellant on Mars and finding the right propellant. Those changes in the actual mission design will help drastically break down the price, Musk explained.

As of now the mission is still years off, and even with Musk’s wealth, it’s going to take more than money to get humans to Mars.