When you are starting a new business you don't want to go after giant markets. You want to go after small markets and take over those markets quickly.

Since 1920, the vast increase in welfare beneficiaries and the extension of the franchise to women - two constituencies that are notoriously tough for libertarians - have rendered the notion of "capitalist democracy" into an oxymoron.

For a new payment product, you always have to ask, how much better is it than the current solution? So when we started Paypal, for eBay micro merchants, it was much better than getting the 7 to 10 days process of cashing a check in the mail. When you look at stores or physical worlds, places, a lot of these places are already set up to take cash or credit card. Apple Pay may be an incremental improvement, maybe a little bit better. But when you have something that's pretty good and you go to something that's perfect, sometimes it's very hard to drive adoption because the delta is not that big.

By the time a student gets to college, he's spent a decade curating a bewilderingly diverse résumé to prepare for a completely unknowable future. Come what may, he's ready-for nothing in particular.

But the indeterminate future is somehow one in which probability and statistics are the dominant modality for making sense of the world. Bell curves and random walks define what the future is going to look like. The standard pedagogical argument is that high schools should get rid of calculus and replace it with statistics, which is really important and actually useful. There has been a powerful shift toward the idea that statistical ways of thinking are going to drive the future.

I think in my twenties I tended to think of all people as sort of more or less alike. In now think that people are really different in all these subtle ways that are very important.

As you craft a plan to expand to adjacent markets, don't disrupt: Avoid competition as much as possible.