It's not just advertisers by a long shot, they aren't even the main customers in most respects now. Governments want all of that information and buy it, as do other commercial interests, including security consultants and contractors like Palantir.
Governments can use go betweens to buy the information too, China for instance, is likely getting every single piece of information sold by data brokers. The entire thing is a joke, on us, because it's not about the kids, it's about locking down the internet and crafting social scores based on everything we have said or done online and off run through half baked ai threat detection.
Starmer is a fascist cunt that will hand the government to openly fascist cunts, but yay, go team! /s