At the heart of the argument between the EU and Facebook is a question which could determine the very survival of the social media giant.
For though Facebook is one of the world's biggest companies, worth almost half a trillion dollars, that value is based almost exclusively on what it does with users' data.
Or, as Mark Zuckerberg responded at a Senate hearing in April when asked how Facebook remained free: "Senator, we run ads."
If Facebook can continue to use user data to target those ads with precision, then it will continue to make - and be worth - a fortune. If, however, either regulators or users get fed up with their details being used to sell stuff, the tech giant really isn't worth all that much.
Amazon's data harvesting, for example, is also being scrutinised by the EU. But Amazon's dominance is driven not just by data but also by an enormous physical delivery infrastructure (and in web hosting).