"You're forever a statistic, worth a few pence to Facebook, and a few quid to everyone else who buys data."
Who is "you" in this context? If FB don't actually have a registered user as an anchor, they must be inferring the existence of non-FB people. It is an open question whether that inference is correct. It is entirely possible that some of "you" is distributed amongst your social near neighbours and "you" don't exist within FB's world model as an entity in your own right. Equally it is possible that "you" are distributed amongst several shadows and FB don't realise they are the same person.
Lastly, and with reference to the earlier comment that FB offer to delete all that they know about you if you use a page on their site to "sign in and hit delete", this would only delete what FB know about the person they think you are when you do that. Since we don't all come with UUIDs stamped on our foreheads, that may not be all they know about you and it may be stuff they know about someone else who they've confused with you.
In this public debate, I think there is a real danger that every just believes the claims FB make about their omniscience. These claims are made by FB to sell their services to advertisers. We can't disprove the and FB can't prove them and FB have no incentive to under-estimate their own cleverness. Therefore, it would be wise to assume that they are probably exaggerated.