In the light of FB incident, here are my two cents.
I am using your product, you have all the information about me.
It's okay.
You sell it to third party.
Not okay.
They with your help harvest the information and manipulate everyone.
Neither you are God nor I am stupid.
Fuck off.

P.S. this post is for all those who are addicted to social network.

Not too many Facebook addicted people here. The place is a shithole I check once a month at best.

You agree to sell your soul to FB while sigining up. Have you read their terms and conditions?

Example of how selling data to third party might be good (IMO):
Let's take Revolut, for example.
They state, that sell you info to the third party and you need to agree to that while registering. But instead you have free transactions, no fees, cool features that are usually paid and so on.
And your sold data is anonymous.
In my opinion, this is a good option on how to treat your users.
But the way FB doing it is... Ugh, it's so wrong :/

I’m surprised at how many people are surprised.

Facebook sells your data. That’s basically their business model.