Affirm CEO Max Levchin on what it was like being around Elon Musk and the rest of the PayPal Mafia in the company's early days: "We knew the people in the room intimately. We literally exchanged pheromones by hanging out in these sweaty rooms brainstorming, screaming at each other, spending a lot of time at whiteboards and declaring the other person's ideas idiotic." "We knew the true version of that person. The ultra philosophical Peter Thiel, the go all in every time Elon Musk, the these…