Great tech opportunities happen only once.

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.

Technology is probably the single biggest driver of productivity gains for the developed countries. For example, I think it's much more important than free trade.

Rivalry causes us to overemphasize old opportunities and slavishly copy what has worked in the past.

If you invest in Microsoft or Oracle, or a number of other companies for that matter, you're fundamentally making a bet that there's going to be no innovation. So an investment in Microsoft is a bet that the operating system is going to stay the same, it won't be replaced by Linux, Google Docs, or a mobile platform like iOS or Android.

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.

If the slogan for Google is 'Don't be evil', then the slogan for Uber is 'Do a little bit of evil & don't get caught.'