The so-called 'PayPal mafia' represent the best, worst, and most controversial aspects of Silicon Valley

When David Sacks left PayPal, shortly after eBay paid $1.5bn (£1.2bn) for the company in 2002, the first thing he did was finance a movie. The result, 2005’s Thank You For Smoking, became a sleeper hit, and returned its $10m budget many times over.

The dotcom bubble had burst, and Sacks could have put his tech days behind him. But as one big screen mobster famously said, just when you think you’re out, they pull you back in. Sacks went on to found Yammer, a social network for offices. It was later bought by Microsoft for $1.2bn.

This Cosa Nostra does not go around breaking windows, but in Silicon Valley, it is just as notorious. Sacks is one member of the “PayPal mafia”, the network of the first employees at the payments company who have gone on to enjoy immense wealth and influence in the tech industry.

Its don, Peter Thiel, PayPal’s former chief executive, was the first outside investor in Facebook, and remains one of tech’s most powerful venture capitalists. His consigliere and co-founder Max Levchin backed the likes of Stripe and Pinterest.

The family also includes Tesla’s Elon Musk, LinkedIn’s Reid Hoffman, and the founders of YouTube, Yelp and Palantir. Today, the roughly two dozen members continue to finance one another, sit on each other’s boards, and work at each other’s companies.