In my eyes, the most important argument for protecting your data in any case is that you lose the control on how the data is interpreted by anyone. Privacy just limits the possible (legal) perspectives anyone can have on you. Any data you lose can be used as facts, even if they are out of context, incomplete or perceived or stored in a way that distorts the data. Any data collected leads to reversal of evidence. And it is much harder to fight that, because you have to attack the technical aspects on how the data is collected and/or what is wrong with the data (by giving up more information).