Most of us couldn't even dream of spending $172 billion in our lifetime — but for Jeff Bezos, whittling away his vast fortune is easy.
The Amazon founder, who is also the world's richest man, recently revealed his plans to spend almost every dollar of his incredible wealth on space travel.
In an interview with Business Insider, Bezos said he was now spending around $1.3 billion each year on his space exploration company, Blue Origin.
Interview Mathias Döpfner — who is CEO of Business Insider's parent company, Axel Springer — said he had previously interviewed Bill Gates, who said it was difficult to find "appropriate" ways to spend his money in a way that helped the world.
He then asked Bezos, as the first person in history to be worth "a three-digit amount of billions", what he planned to do with his cash.
"The only way that I can see to deploy this much financial resource is by converting my Amazon winnings into space travel. That is basically it," Bezos explained.
"Blue Origin is expensive enough to be able to use that fortune. I am currently liquidating about $AU1.3 billion dollars a year of Amazon stock to fund Blue Origin.
"And I plan to continue to do that for a long time. Because you're right, you're not going to spend it on a second dinner out. That's not what we are talking about."
Bezos said Blue Origin was his "most important work" — and that Amazon was a secondary interest compared to his space company.
"I am very lucky that I feel like I have a mission-driven purpose with Blue Origin that is, I think, incredibly important for civilisation long-term," he said.
"And I am going to use my financial lottery winnings from Amazon to fund that."
He said Blue Origin would launch humans into space by the beginning of 2019 at the earliest, and that he believed the solar system could "easily support a trillion humans" in the future.
"If we had a trillion humans, we would have a thousand Einsteins and a thousand Mozarts and unlimited (for all practical purposes) resources and solar power unlimited for all practical purposes," he said.
"That's the world that I want my great-grandchildren's great-grandchildren to live in.
"By the way, I believe that in that time frame we will move all heavy industry off of Earth and Earth will be zoned residential and light industry. It will basically be a very beautiful planet."
Bezos, who is married to author MacKenzie Bezos and is a father of four, is known for being otherwise tight with his cash.
He told Mr Döpfner the family had few "guilty pleasures" — but said they had recently splurged on a trip to Norway.
He is also known for treating his wife to clothes and accessories, telling Vogue: "Sometimes I call her and say, 'What's your such-and-such size?' and she says, 'Why?' and I say, 'None of your business!' It delights her."