It’s not “a set of people” anymore it’s you, and there is always more data.
Buy some doughnuts for the office… your health insurance just went up.
You buy a new car which has fancy connected features, but now it sells your driving safety score to your car insurance company.
Buy a vegan ready meal, both vegan food companies and the meat industry compete for your business, you might get a few discounts, but your free will is being influenced.
Credit card companies know where you are spending your money, but not what you are buying.
They have been selling your data but it’s less valuable in the world of store apps and online stores where every search and purchase is linked to your email. Still worth opting out of any “data sharing” options your Credit Card company has though.