You're right, we are the product they are selling and the sites do need us. As long as FB offers compelling products, people will continue to use it, even if it means giving away personal data. This has been a very successful business model that has come out on top in the free market. I don't think there is anything particularly wrong with it. To me, privacy doesn't have any tangible value and is not the same as security. For example, there is nothing private on Steemit - you can even look at how much I have in my wallet. However, Steemit is very secure and you would have to come to my house to find my private key and steal my money. Security trumps privacy, and companies like FB and Google has very strong incentives to keep things secure.