> Free content and services. What do you lose in exchange?
Privacy. What I do shouldn't really be anybody else's business.
An ad-targeted web. IMO ads are a plague on useful content, because everything is about getting views and clicks. This makes actual content less useful and more annoying to consume. It incentivizes posting low effort, watered down content rather than smaller amounts of great content. It also means content creators are trying to please the advertiser, and not me.
Risk of manipulation. Lots of effort has gone into figuring out how to best manipulate people, and when you know who somebody is and how to best tailor any given message to them, you can get pretty far. I'm quite sure that I also have buttons that can be pushed if somebody knows how, and I don't particularly like the thought of that.
And why the heck would I want to give my data to a bunch of random companies? What's the benefit in it for me, anyway?
Says who?! I have zero problems sending my private data to the US. I did it for years and I still think is one of the better places to send my private data to. Definitely better than my own country.