There is another problem, beyond the initial ads-based business. This information gathered about you, albeit anonymously, is correlated. This helps train models about groups of people, in order to derive value from group information. It can then be sold to insurances, banks, etc.

Derived information may look like: "Clojure programmers buy a new computer every 3 years on average" "Women in medium socio-economic groups tend to have kids at 31 years old"

But maybe I'm a programmer that cares about waste, and use the hell out of my computers, until it is completely unusable, making them last way longer. Maybe I'm a woman with trouble getting pregnant, and I won't have kids until much later.

Nevertheless, insurances and banks will use that information against me.

This information grouping you take part of, is de-humanizing. Humans are infinitely complex, ever-evolving creatures and categorizing us is profitable business. I do not want to be treated through the lens of the probability of a group I belong to, no matter how small the box.