They can keep trying, argument for the existence of "intellectual property", and demand AI to pay them for being artists. They can debate from various perspective relating to human rights or humanity, but bottom line, this is really just about money. They don't really care if someone "steals" their reputation as long as get paid enough.
I think this AI challenge to artists is one way to surface how ridiculous how "stealing" is not the same as "lying". So give credit to where credit's due, is more against lying, when copyright is involved, rather than "stealing". But in the end, give unto Caesar Caesar's.