I sympathize with artists who might lose their income if AI becomes big, as an artist it's something that worries me too, but I don't think applying copyright to data sets is a long term good thing. Think about it, if copyright applies to AI data sets all that does is one thing: kill open source AI image generation. It'll just be a small thorn in the sides of corporations that want to use AI before eventually turning them into monopolies over the largest, most useful AI data sets in the world while no one else can afford to replicate that. They'll just pay us artists peanuts if anything at all, and use large platforms like Twitter, Facebook, Instagram, Artstation, and others who can change the terms of service to say any artist allows their uploaded art to be used for AI training - with an opt out hidden deep in the preferences if we're lucky. And if you want access to those data sources and licenses, you'll have to pay the platform something average people can't afford.