The way I've always seen it is that they'd never directly sell user data because that is their most valuable and prized asset. It's what allows them to sell targeted access to users for so much money.
sort-of agree .. the accuracy, timeliness and completeness of any real-world data will change.. many comments assume some kind of perfect knowledge, which is never the case. Selling snapshots of current profile understanding is not only better business, but can also evolves with the enterprise over years; meanwhile selling raw user profiles as a whole is more like "damaged goods at a discount" for quick profit maximizers. This said, "surveillance capitalism" is rife and inherently a step backwards from a democratic society IMHO due to information asymmetry, secrecy and income generation.
