I think this points out that AIs clearly do not work like human brains. Human brains do not need all of the content of humanity to produce a replica of art station mediocre.
Do they have a choice? A handful of corporations have captured all the network effects. If you need to reach an audience to do your job or find your "friends", what other choice do you have but to give your data to them?
If they aren't close why do you care?
Alternatively, what would make more sense is to participate in communities gated by these networks but then it's your choice to be there.
I don't personally have this problem, but my observation is that most social relationships are somewhere in between closest friends and don't care.
My own concern is more about participating in professional, neighbourhood, civil society or political communities. Choosing not to be where they have decided to congregate means not being able to do my job and not making my voice heard where many decisions are taken that affect me.
Many people who aren’t that privacy conscious would however object to lots of companies, big and small, sucking their content into their databases for their own uses, then republishing after it’s passed through a few AI models.