Earlier quoted context omitted.
Because we are humans and our capability of abusing those rights is limited. The scale and speed at which LLMs can abuse copyrighted work to threaten the livelihoods of the authors of those works is reason enough to consider it unethical.
I don’t think it is. What you describe is similar to any other industry disruption, and I don’t think those are unethical. I’d actually argue that preventing disruption is often (not always) unethical, because you artificially prolong an inefficient or inferior alternative.
Obviously this is a bit facetious, but basing your ethical framework on utilitarianism and _nothing_ else is pretty radical.