A sober, humble lifestyle dedicated to service is worth far more than thousands of followers on social networks.

In retrospect, I do think it's fair to say that we were overly idealistic and focused on more of the good parts of what connecting people and giving people a voice can bring.

I think we basically saw that the messaging space is bigger than we'd initially realized, and that the use cases that WhatsApp and Messenger have are more different than we had thought originally.

We talk about this concept of openness and transparency as the high-level ideal that we're moving towards at Facebook. The way that we get there is by empowering people to share and connect. The combination of those two things leads the world to become more open.

Our role is to be a platform for making all of these apps more social, and it's kind of an extension of what we see happening on the web, with the exception of mobile, which I think will be even more important than the web in a few years - maybe even sooner.

It used to be the case, like you'd switch jobs, and then maybe you wouldn't keep in touch with all the people that you knew from that old job, just because it was too hard. But one of the things that Facebook does is it makes it really easy to just stay in touch with all these people.