Going from PayPal, I thought: 'Well, what are some of the other problems that are likely to most affect the future of humanity?' Not from the perspective, 'What's the best way to make money?'

I've actually made a prediction that within 30 years a majority of new cars made in the United States will be electric. And I don't mean hybrid, I mean fully electric.

The extension of life beyond Earth is the most important thing we can do as a species.

Fear is a hard thing to deal with. I feel it quite strongly. If I think something is important enough, I'll make myself do it in spite of fear. But it can really sap the will. I hate fear, I wish I had it less.

If anyone thinks they'd rather be in a different part of history, they're probably not a very good student of history. Life sucked in the old days. People knew very little, and you were likely to die at a young age of some horrible disease. You'd probably have no teeth by now. It would be particularly awful if you were a woman.

I hate writing about personal stuff. I don't have a Facebook page. I don't use my Twitter account. I am familiar with both, but I don't use them.

If you had to buy a new plane every time you flew somewhere, it would be incredibly expensive.