Authenticity.
A lot of it has to do with luck, Graham said, but if you had to boil it down to one quality to look for, authenticity would be the most important one.
"You're looking for people who are real friends," he said to Chang. "Not just for people who got together for the purposes of this startup. You don't want people who were in it just for the money."
Graham cited an example, saying that if Facebook CEO Mark Zuckerberg would have sold his company to Yahoo back in 2006, it would never be the massive social network it is today.