Facebook’s data is way more valuable to Facebook; it doesn’t sell data to third parties. If you think they’re going to sell the non-monetisable data to third parties, you have to believe they’re willing to introduce this (which is likely to be unpopular) in apparent compliance with data protection laws, while still flagrantly violating them in secret, without any of their many employees nor any of their partners’ employees blowing the whistle (and Meta as a company leaks all the time). If they were doing that, why would they bother setting up the fake “pay to not be tracked” flow, when they could pretend to honour people’s free requests not to be tracked?