[XCSme]

I am usually not worried about my personal privacy but the power that aggregated data gives to a company.

If they wanted, they could create or destroy businesses based on the data they have. Let's say they want to create a competitor to a small pop-corn stand. They could see the profiles of all people who go to that existing stand and make it look like something they wanted (eg. based on their YouTube history). They could check the paths they take daily, or the route they take to that stand and put their own in a better spot (eg. based on location history). They could only open the stand or promote it when people are really craving, for example after work or after a gym workout (eg. from the Fitbit data).

You get the point, the idea is that once you have all those insights into a mass of people, you can easily control them into buying your product or doing what you want them to do, while they think it's their idea to do that.

In general, people are very easy to influence. If I just mention the words "FIFA 20 on PS4", you are very likely to have all those thoughts about gaming and maybe actually want to start playing FIFA, even though before you had absolutely no intent to do so.