The argument here is founded on motivated reasoning.

Copyright was founded on similar principles to property rights, it encourages desirable economic by ensuring investment in RnD doesn’t have a free-rider disincentive. Whether it’s the right tool for the job and how enforcement carries out its a another matter. While these laws for property and IP aren’t without issues they do address actual problems.

Personally I would be more open to the idea of open AI flouting copy rights if they weren’t planning on taking a portion of the claim of other peoples creations used via the product while failing to properly compensate the sources of its training data.