"We both certainly share a curiosity about the world," says Buffett, speaking at a Facebook live event broadcast from Columbia University and moderated by Charlie Rose.
The two first met in 1991 at a dinner that, Buffett jokes, Gates' mother had to convince him to attend. At the meal that would launch a long and enduring friendship, Gates' dad asked the two men what they felt their most important quality was.
They each had the same answer: curiosity.
Their friendship was almost instant, largely driven by the shared desire to learn more about their environment.
"We find the world just such an interesting place, so we like to compare notes," says Buffett, who founded Berkshire Hathaway and has an estimated net worth of $73 billion.
Curiosity is "an amazing thing," says Gates, "where you try to predict what is going to happen, and then, when it doesn't, you think: Well, that drug didn't get invented, that stock didn't go up, that approach wasn't popular. What is it about my model of the world that's wrong? Who could I talk to? What could I read?"
Both men educate themselves constantly to satiate their curiosity.
"This is a phenomenal time to be a curious person," says Gates, who co-founded Microsoft and has an estimated net worth of $84 billion. "The information that is out there! My biggest problem is that I stay up too late because I am reading and then I am a little bit tired the next day."
Buffett has also always been a reader. A Columbia alumni, he said he lived his college days in the school library. Today, at 86, Buffett says he reads between five and six hours a day, and particularly loves biographies.
"You can't get enough of reading," says Buffett.