Tracking usually happens across websites, meaning the information is shared with third parties outside the people running the website where you accepted the cookies. Knowing your interests, behavior and preferences makes you prone to manipulation. The selection of information shown to you will be crafted such as it maximizes engagement. For example, showing you information that upsets you, in order to get you to react. Or just information with a slant or spin to influence your opinion. Nobody is immune to being affected by the distribution of what they are being shown.

These popups aren't about cookies but really about spying. It seems you have nothing to hide. I understand: I also don't. However, the problem with spying is not about individual secrets but about the society and democracy.

Lack of privacy harms journalism and activism, making the government too powerful and not accountable. If only activists and journalists will try to have the privacy, it will be much easier to target them. Everyone should have privacy to protect them. It’s sort of like freedom of speech is necessary not just for journalists, but for everyone, even if you have nothing to say.

The banner is not just about cookies, but also about data sharing, so by accepting you increase the amount of your data that can be leaked.

These banners handle both ePrivacy consent for cookies etc, but also GDPR Art. 6(1)(a) for processing purposes (personalised ads, measurement, audience insights, precise geolocation, even device fingerprinting).