Actually you don't even have to be one of its users! Facebook has what they call "shadow profiles" for tracking people who haven't yet created Facebook accounts. That's how they instantly show you everyone you know when you finally create a FB account. You have Facebook cookies on your computer even if you have never visited facebook.com. Try deleting them. Within 30 minutes of browsing random web sites I guarantee you'll once again have facebook cookies. They track everything you're doing online even if you're not one of their users. Then they buy offline data about you from other companies, to complete their profile of you.
Sadly they only way to put an end to all this is by hoping the European Union will introduce new laws -- the only government that actually represents their citizens, as opposed to big businesses.