I suspect that most people do not in fact have a Facebook account. Last I checked, world population was over 7 billion and Facebook did not have 3.5 billion accounts. Or did you mean "most people who live near where I live"? But even there, the existence of Facebook shadow accounts means they will stalk you even if you do not have an account.

As a further point of fact, Facebook (and Google; Facebook is not alone here) stalks even people who _can't_ have a Facebook account. For example, children under 13 in the US.