As an author from Wired tried to sell his personal data and found out it isn’t worth much, some economists made the following valid remark.
Yet data can be worth a good deal in the aggregate — just ask some of the major tech companies. The economics here are a bit like the economics of voting. If it were legal, and you tried to sell your vote and your vote alone, you might not get much more than 0.3 cents. That vote is unlikely to prove decisive. Yet average and marginal value do not coincide. If someone could buy a whole block of votes, which in turn could swing an election, the price could be much higher.