"Privacy" in the modern sense is less about protecting you from personal embarrassment or financial loss, and more about protecting society from the dangers of mass data collection.
Historical examples of mass datasets that were misused:
- The Nazis used demographic records (birth, death, marriage records, etc.) to identify Jews and other undesirables in conquered countries.
- Japanese Americans were identified for internment in part through illegal use of census information.
- The Rwanda genocide was facilitated by tribal information being printed on drivers licenses.
In none of these examples were the data collected for the evil purposes it was eventually used for. In some cases, the evil purposes were completely forbidden by the rules governing the data, but they were used anyway.
Information is a form of knowledge. Knowledge is power. And power in the wrong hands is dangerous.
That's what dihydrogen monoxide poisoning does to average IQs.