Uh... Are you saying simply using social media is endorsing stealing personal information to train LLMs?
Of course not. No "stealing" is happening. People are posting content on an open protocol that permits anyone to read it. Exactly as intended.
Personally, I feel like there's no stopping them, so what am I supposed to do, stay silent?
If you do not want to be heard then yes, I suppose you could stay silent. That would indeed accomplish that.
You could also find a social media platform whose content is locked behind a walled garden of some sort that makes it more difficult for your posts to be seen by the public. But that's antithetical to how the Fediverse works, you want someplace very different from here if that's how you want to approach this.
Basically, you are on a platform that's specifically designed to broadcast your comments far and wide without restriction, and then you're getting upset that someone you didn't want to hear your comments is hearing your comments. I'm not sure what you expected.