I understand what you are saying but I would argue that there is a huge difference between selling your data to advertisers to try to target you with ads, the traditional approach, vs try to feed you extremist posts to drive your engagement with the platform by making you a more upset person.

I would argue that the problem is not that it is free but that it is run for profit. Our data has value, services could pay for themselves if they were co-owned by the users. If we didn't have the incentive to maximize profit at the expense of the user but instead to provide user data for a fee with reasonable privacy controls we could all be better off.