> Once they tap into that for PPC/paid ads,
If they start showing ads based on your prompts, and your history of "chats", it will erode the already shaky trust that users have in the bots. "Hallucinations" are one thing, but now you'll be asking yourself all the time: is that the best answer the llm can give me, or has it been trained to respond in ways favourable to its advertisers?
This is the exact same issues Facebook/YouTube/etc had with ads. In the end, ads won.
Google used to segregate ads very clearly in the beginning. Now they look almost the same as results. I've switched to DDG since then, but have the majority of users? Nope. Even if they're not using ad blockers, most people seem to not mind the ads.
With LLMs, the ads will be even more harder to tell apart from non-ads.