> I guess I can understand that if I have to see ads at all, may as well make them personalized
I think this is the greatest lie the ad industry has foisted on us, and unfortunately I see a lot of people fall for it.
We hear the word "personalized" and we think "relevant" or "interesting". That if you _have_ to see an ad, at least let it be one that tickles your fancy.
Yet interesting and relevant is _not_ what ad tech is optimizing for. Rather, ads are optimized for _conversion_; the likelihood that a user will be converted into a "sale" (where "sale" can range from simply clicking the ad, to buying a product, to subscribing to a service, etc. Whatever is most important to the ad buyer and measurable.)
Optimizing for conversion is _not_ the same as optimizing for being relevant or interesting. Instead these ads are being optimized to exploit whatever weaknesses you, the targeted user, may have. How can they _trick_ you into converting.
It's the same problem we see with social media. Social media companies optimize for engagement, which means they get filled with the baser human emotions in ways that get people addicted, regardless of its cost to the user or society as a whole. Ad tech is doing the same thing, and in many ways "engagement" is synonymous with "conversion". Ad buyers are paying ad markets to do absolutely whatever it takes to engage a user in the ad buyer's desired activity. Come hell or high water, those ad markets will convert you and they will consume as much data and processing power as necessary to find a way to do that.
All this to say that ad tracking is not about making ads more interesting to a user, more palatable, like many seem to believe. It's about using _your_ personal data to _manipulate_ you.
Ad tracking is finding ways to tailor a drug to the specific user to maximize the seller's profit.