Bill Gates' obsession with reading started early on. As a kid, his parents gave him "an arbitrary budget to buy books, so I got to read a lot," he told Harvard students during a Q&A last month.

And part of his massive success is thanks to the fact that he maintained the curiosity he had as a kid, he says. "A lot of people lose curiosity in their 20s or 30s," the self-made billionaire and Microsoft co-founder said. "So if you hand them a big, thick book, they're like, 'What? Am I going to read that?'"

Specifically, "people don't make time to read what's fairly academic and super profound," Gates continued, but those are some of the most important books to dive into.

He recommends reading Steven Pinker, the author of two of his all-time favorite books: "The Better Angels of Our Nature" and "Enlightenment Now."