Facebook is quite entrenched and has a network effect. It's hard to break into a network once it's formed.

SpaceX has the potential of saving the U.S. government $1 billion a year. We are opposed to creating an entrenched monopoly with no realistic means for anyone to compete.

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.

We could definitely make a flying car - but that's not the hard part. The hard part is, how do you make a flying car that's super safe and quiet? Because if it's a howler, you're going to make people very unhappy.

I think the high-tech industry is used to developing new things very quickly. It's the Silicon Valley way of doing business: You either move very quickly and you work hard to improve your product technology, or you get destroyed by some other company.

The lessons of history would suggest that civilisations move in cycles. You can track that back quite far - the Babylonians, the Sumerians, followed by the Egyptians, the Romans, China. We're obviously in a very upward cycle right now, and hopefully that remains the case. But it may not.