Well if you live in a democracy you should. It's not about your data alone, its everyone else's. It's social media company XYZ determining how each individual is going to vote, then, on election day sending all people on one side get out and vote messages, and sending people on the other side a tsunami of unrelated bs to make sure they don't know about the election. Or push a bunch of fakenews to make them feel both sides are the same and why even vote?
Do this in a couple key areas and you only need to hit a few tens of thousands of people to turn a presidential race.
We know it can be done because it already has been. If you live in a democracy you should care a good deal about privacy, even if you somehow have nothing to hide
You should read Exhalation by Ted Chaing if you haven't already. It's a quick read