Paranoia is the fear of things that are highly unlikely to happen. And it roams also in the internet.
However that knowledge (also about customers) is power and this knowledge can be used against your interests is not paranoia but a matter of fact. And fairly well known substantiated with scientific research.
There is a whole industry researching customer habits and designing marketing strategies to make you buy things that the company wants you to buy.
If a company knows you might be willing to pay more they will offer you a worse deal. Dynamic pricing is a reality. Not yet in all business branches, but it is increasing and some cases were well documented.
If something is profitable, legal and not too likely to destroy the reputation of a company, then they will do it, no matter how "moral" it is.
Only information that does not exist cannot be used again you.
Privacy by design (
https://en.wikipedia.org/wiki/Privacy_by_design) is actually a common sense principle, not paranoia.
Paranoia is e.g. not using fluorinated toothpaste, categorically not using vaccines and similar ideas.