While you aren't wrong, in this day and age it's not enough to simply pay. Even if you pay for something, you are still the product being sold. Why would a company leave money on the table, when violating people's privacy is profitable and there is no backlash?
Ethics?
In a society which doesn't care enough and a legal system that doesn't punish unethical behaviour any company tapping unethical revenue streams in addition to the ethical ones will have a competitive advantage and given otherwise similar conditions eventually outperform ethical companies. Once a sole actor goes down that path it puts a lot of pressure on all other actors to throw ethics overboard as well as otherwise their company's survival and in extension their livelihood will be threatened. This is why we can't just rely on market forces sorting everything out, consumers making decision, etc. but have to actively legislate to protect our privacy and personal rights.
It's not this day and age. Analytics and data mining of customers data is as old as business. 2000 years ago merchants were also tracking who's buying what, in what city, what time of the year, etc.
It's waaaaay more efficient nowadays and way more creepy, but it's not a new invention.
What you're describing with that quote isn't cynicism. Especially as far as FB is concerned. That is absolutely business as usual for them and has been for years.
"Cynical" usually implies an element of assuming the worst when such an assumption is far from certain. In this case I think the assumption is spot-on and not at all surprising.
Just because you've heard it before doesn't make it false. I hope your naivete represents a minority perspective.