Facebook is but one of a large number of companies that hold private data and use it to their own advantage.
In fact, even without a facebook account they'll know about as much about you unless you've blocked their domain/ips on all your devices because those like buttons are everywhere.
Why do you feel the need to justify yourself about not having a fb account? Simply blackhole and ignore them, then get on with your life and if people ask you why not 'because I don't trust them' should be more than good enough, no need to go into paranoid fantasies about what they could do.
If facebook wants EU style data protection / privacy laws in the US then they should definitely try to sell your private data to insurance companies. I'm pretty sure that would sway even the most pro-business anti-consumer legislative body.
