When billionaire Elon Musk was a 17-year-old college student at Queen's University in Kingston, Ontario, he had a brief stint where he only spent a dollar a day on food — and he successfully got by.

"My threshold for existing was pretty low," he tells Neil deGrasse Tyson in a 2015 interview on the podcast StarTalk. "So I figured I could be in some dingy apartment with my computer and be okay and not starve."

The CEO of SpaceX and Tesla describes how, from a young age, he focused on things that would affect the future of humanity, like electric cars, solar power and sustainable consumption. So shortly after he moved to Canada from South Africa, he tried this experiment to figure out if could really live spending so little on food.

As it turned out, a $30 CAD monthly grocery budget proved sufficient.

"You sort of just buy food in bulk at the supermarket," he says, though he admits that "you get really tired of hot dogs and oranges after a while." Pasta and green peppers were staples of his, too.