> nothing in Bitcoin prevents someone from generating the wallet of someone else

Maybe nothing in Bitcoin does, but among many other things the heat death of the universe does. The probability of finding a key of a secure cryptography scheme by brute force is purely of mathematical nature. It is low enough that we can for all practical intends just state as a fact that it will never happen. Not just to me, but to absolutely no one on the planet. All security works like this in the end. There is no 100% guaranteed security in the sense of guaranteeing that an adverse event will not happen. Most concepts in security have much lower guarantees than cryptography.

LLMs are not cryptography and unlike with many other concepts where we have found ways to make strong enough security guarantees for exposing them to adversarial inputs we absolutely have not achieved that with LLMs. Prompt injection is an unsolved problem. Not just in the theoretical sense, but in every practical sense.