Well, would you rather the site just not exist then? Because I'm pretty sure that most of these sites already aren't making much money. If you make it much much much harder for them to get money then they won't survive.
If you can't run a website without literally violating the users basic human rights, then just don't.
Correct, and thankfully website operators don't get the choice to violate users privacy without consent.
If a shopping center would want to distribute surveillance camera data to 'trusted partners' for marketing research without informed consent of the customers, that would definitely be a GDPR violation, and there would not be a "if you don't like it then don't go to that supermarket" situation but "if your supermarket can't survive without that income, then tough luck".
Certainly the bar owner cannot distribute the videos without explicit consent. And yes, that can be problematic in many cases (for examples, capturing faces of people in a concert).
When you give up a small piece of seemingly insignificant data about yourself a million times per year, the aggregate is wildly more significant than the sum of those pieces. When you and everyone you know give up the aggregate of each persons aggregate information, again, its value is compounded. Finally, since no one has any insight into nor control over where their data ends up or how it's used down the road, the danger of sharing is even less evident.
Good can and does come from transparency, but this is one-way transparency. It's top-down and is begging for abuse. If we had a truly voter-representative government, it would have already created laws to mitigate the easy-to-anticipate problems that arise from massive accumulations of personal information, and we would no doubt have a better, if less profitable, WWW as a result.