To not give them your data, you can't interact in their ecosystems. Their ecosystems are the community writ large, so by voluntarily removing yourself from those ecosystems, you're voluntarily removing yourself from the parts of society that they've squatted on. Ergo, removing yourself from society (with a sprinkle of hyperbole, since it was sarcasm)
Without you having signed up to Facebook, if anyone you know who has your phone number has signed up and shared your contact info, then they know your name, who you know, your phone number, which they can then use to associate you to any online interaction where you've also given your phone number. They have an idea of the demographics you belong to, political stance (not having a Facebook or Instagram gives them a lot of info for that), and a general vibe of who you are. Source: The exposure after the Cambridge Analytica Scandal
You pointing out that maybe the victims are to blame for their data being in the hands of megacorps surely must imply that you think personal responsibility is the only recourse we have for this. But maybe I read that wrong and you just had no further thoughts beyond what you literally wrote down. Victim blaming for the game of it.