They will collect it from everyone to prove your age.
The question only that is it worth the gamble by Meta, as in how many people would rather leave the sites (from Whatsapp to Insta to Facebook) than give them their ID
Now, based on their ruthless disregard for the law, do you think they're just going to use it to sell your ads?
Plus they are lobbying for it to be someone else's problem they are lobbying for device and OS based age verification.
2. It's onerous for upstarts, so it entrenches Instagram and Facebook.
3. Guaranteed knowledge of who everyone is, and their web browsing activities, furthers their surveillance ends.
4. If you keep people off until they're adults and then throw them in with no guidance, they'll have an even worse time. Which is good for propagandizing.
5. They get to collect biometrics from everyone, even the underaged ones who attempt verification. All the better to build panopticon, along side Clearview and Flock.
6. The Heritage Foundation wants it, and everything else on Project 2025 has been proceeding as planned with lackluster resistance, so why would this be different? (Spoiler: the next part is calling everything they don't like, such as LGBT people being visible or alive, as "harmful" and using these new surveillance tools to deal with that.)