All this invasion of privacy and still little evidence that user targeted advertising is substantially more effective than simple content based advertising.
Quote: "So successful, by the way, that between 2000 and 2004 with their IPO [Initial Public Offering] documents going public, the first time we got to learn exactly what the impact of this new logic was. And the impact was a revenue increase of 3,590%, just during those years 2000-2004."
source: https://www.econtalk.org/shoshana-zuboff-on-surveillance-cap...
Tracking advertising costs the advertiser more (and makes the ad provider a lot more), but there's little evidence to suggest it's significantly more effective than content advertising. And this isn't even accounting for the enormous social cost of private surveillance.