No it isn't theft. It's copyright infringement, which is decidedly not theft.

These companies used everyone else's copy written material for "training" but that's fine because it was only taking that data from everyone. But once someone takes data from them, IP or not, they claim to have been harmed. But don't claim they're harming anyone else...somehow.

They're not paying anyone for their IP, and no one should pay them for their IP. It isn't a problem for them, so it's not a problem for anyone else to do it to them.

Do we honestly believe Microsoft doesn't have ANY IP owned by others in their training data? They've managed to completely destroy their own protections, I can't see how an actually competent Judge could see it any other way. Sure you'll find corrupt Judges that'll side with them, but that doesn't make it correct.