You couldn't be more wrong, so many people are afraid of stuff like their old Tinder profile leaking etc. So having a law that forces companies to delete your profile rather than keeping it around forever is really important to people. You can see leaks from another site like that embarrassing a lot of people who thought that they had deleted all data related to them, they certainly would have wanted GDPR back then.

People don't care about most data, you are right about that, but they care a ton about some data.

GDPR is just about that, make you own your own data rather than companies owning it. Companies has to ask for it rather than just taking it, and you can revoke that right at any moment and the company has to comply.