There is a lot of money to be made via LLMs (which is really what the OP is referring to), and that is not from sig deals. The creators of LLMs want their models to be relevant and accurate, so I somewhat understand why some might use the forum to create LLM-created posts, although there are probably some ethical issues in doing so.

Anything a LLM says is not plagiarism. If there is a topic that I find interesting regarding something I don't know a lot about, I might read articles from what I believe to be reputable sources, and I might paraphrase information that I find across several sources in my post. That is essentially what a LLM does.