Words can change meaning, but whether or not they actually do is a social function of how they are observably used. Words can also have multiple meanings concurrently. When it comes to the word "steal" in these discussions, people generally are arguing past each other in regards to the single definition they're thinking of.
Of course, you can assert that the meaning of "steal" only applies to physical items. You are well within your right to do so. You'd be wrong, but you can do it.
> people generally are arguing past each other in regards to the single definition they're thinking of.
It's more than that. By claiming that copyright infringement isn't stealing, they're usually doing so to justify such behavior: if the original thing remains with the owner, it couldn't have harmed him, could it?
I agree, someone certainly has the right to have an incorrect understanding of that the word "wrong" means.
To be fair when someone tries to shift the meaning of words everyone doesn't just have to go with it to appease the large corporations trying to do that. I of course don't mean intellectual property rights or copyright infringement, you can perhaps apply the word "steal" there, not when talking about LLM traces which are currently legally uncopyrightable, though. Unless we're actually talking about someone breaking into Anthropic's servers and stealing their files, then again... if you do that you can always just blame the LLM you used.