It's a juicy thing to say we're building a phone, which is why people want to write about it. But it's so clearly the wrong strategy for us.

The main Facebook usage is so big. About 20 percent of the time people spend on their phone is on Facebook.

The question isn't, 'What do we want to know about people?', It's, 'What do people want to tell about themselves?'

Think about what people are doing on Facebook today. They're keeping up with their friends and family, but they're also building an image and identity for themselves, which in a sense is their brand. They're connecting with the audience that they want to connect to. It's almost a disadvantage if you're not on it now.

My friends are people who like building cool stuff. We always have this joke about people who want to just start companies without making something valuable. There's a lot of that in Silicon Valley.

It's really easy to have a nice philosophy about openness, but moving the world in that direction is a different thing. It requires both understanding where you want to go and being pragmatic about getting there.