Are there any rights you think should supersede contracts?
That is beside the point I’m making. Facebook acknowledges the right to privacy by giving you the choice to pay for the service rather than giving up your data. In my view, this should be completely acceptable by the GDPR. No-one is forcing you to sign up to facebook, so you do have a completely free choice to (1) either not give up your data and not use facebook; or (2) not give up your data and pay for the service; or (3) give up your data and pay for the service that way.