There's an expression that says if it's free, you're the product. That's exactly what you're describing. I think we need to be aware of this. When we buy a product and they ask us our date of birth and tell us it's because they're going to give us a discount on our birthday, that's exactly what's happening. We're given a small discount and that information is used.
It's important to make people aware of this phenomenon so they know, even if they feel it's free, that in some cases they're giving up a fundamental part of their identity, their personality.
We need to be aware of this fact and avoid seeing it solely as an advantage. Indeed, one should not simply sell or trade one's privacy. Even if consent is given correctly, we must always be aware that it is a fundamental part of our individuality. That's an important point.