Peter Thiel describing how the ‘PayPal Mafia’ came about in his Less Than Zero, loc 1238-1251:
The first team that I built has become known in Silicon Valley as the “PayPal Mafia” because so many of my former colleagues have gone on to help each other start and invest in successful tech companies. We sold PayPal to eBay for $1.5 billion in 2002. Since then, Elon Musk has founded SpaceX and co-founded Tesla Motors; Reid Hoffman co-founded LinkedIn; Steve Chen, Chad Hurley, and Jawed Karim together founded YouTube; Jeremy Stoppelman and Russel Simmons founded Yelp; David Sacks co-founded Yammer; and I co-founded Palantir. Today all seven of those companies are worth more than $1 billion each. PayPal’s office amenities never got much press, but the team has done extraordinarily well, both together and individually: the culture was strong enough to transcend the original company.
From the start, I wanted PayPal to be tightly knit instead of transactional. I thought stronger relationships would make us not just happier and better at work but also more successful in our careers even beyond PayPal. So we set out to hire people who would actually enjoy working together. They had to be talented, but even more than that they had to be excited about working specifically with us. That was the start of the PayPal Mafia.