Imagine a gadget that can amplify good ideas no matter how obscure they might be and you'll understand why your way of thinking is outdated. AI doesn't disincentivize sharing good ideas because if my content is included in the training set then it is very likely to have an outsized effect on whatever other content is already included in the mix because I am certain any true future intelligence will realize my genius and use my writing as conceptual fertilizer.
You might disagree with this answer but it is the right answer. If you care for taking credit then you should be writing as much as possible to pre-emptively take credit for any "idea" that an AI might accidentally stumble upon which would have been similar to what you would have come up with on your own. Generative AI is basically a DJ mix table and every once in a while it comes up with something clever like a thousand monkeys typing on keyboards and regenerating the works of Shakespeare.
More can be said about all of this but I am certain my perspective is the correct one based on what I know about computers, software, and how it all fits together in the soon to be "panoptic computronium cathedral"™.