Start filling up Discords with insane AI-generated garbage, and maybe you can devalue the data to the point it won't get sold.
It's probably totally practical too, just create channels filled with insane bots talking to each other, and cultivate the local knowledge that real people just don't go there. Maybe even allow the insane bots on the main channels, and cultivate the understanding that everyone needs to just block them.
It would be important to avoid any kind of widespread conventions about how to do this, since and important goal to to make it practically impossible to algorithmically filter-out the AI generated dogshit when training a model. So don't suffix all the bots with "-bot", everyone just need to be told something like "we block John2993, 3944XNU, SunshineGirl around here."
If we work together, maybe we can turn AI (or at least LLMs) into the next blockchain.