FB isn't just making money on ads it shows you. It has several massive data centers around the country. FB is also an intelligence gathering company, about you personally, then aggregated by what they want to measure correlations with.
I maintain different purpose "smart" phones, but I keep them as dumb as possible, but keeping data = off, location services = off, not able to download apps. Restaurants greeters have to fumble when they want my phone number to tell us when a seat is ready, but I don't have one with me. It's both amusing and scary.
Something else... download a browser that has a plugin that allows you to see what 3rd party scripts are running in the page. Google has scripts in almost every page you visit. It's brutal when you think about how many people will never understand who they potentially shared their transaction with, like google.
If the software you're using is "free", most likely information about you is what you're paying with.