Why are people astonished that Facebook paid 19 billion for WhatsApp. They didn't pay this money for the application. They are after the data. WhatsApp probably owns the biggest database of people and phone numbers. A lot of them aren't even signed up with the service. That's a huge social graph and a lot of people not yet reached by social media. I mean, all my friends who use WhatsApp didn't ask me whether it's ok with me if they send my phone number along with my name to WhatsApp. Forget the NSA, it's your friends who sell your data - for a few free messages.