Is't the fact that data is valuable for somebody, does not mean that it has a cost (price) for me? Spending data is definitely valuable for seller / corporation to know what to produce. I, on the other hand, cannot get money by saving information.
It's not zero sum game, that either I have it or seller have value out of it. Just like with garbage - for me old broken furniture might be a garbage, while for other it's a burning fuel.
That data is used in some alarmingly manipulative ways that directly affect your life.
The only reason it's valuable is because of it's utility to extract value from you. Not just money either but for instance the power to manipulate.
It's not a scientific discovery.
I think the OP is right in that spending data is valuable as a mechanism to figure out how extract more profit, which in the end will have customers paying that price.
However, it doesn't need to be exclusively negative. The data will both show where you can price gouge but also simply where demand is.
Put your coffee shop near a metro stop and sell sourdough bread and people will buy that because they want it isn't exactly negative.