ChatGPT is way above typical CPM, maybe $60-$100. That puts it in the same category as premium YT verticals. If they can sell enough at this price point it would make a big impact, but I'm super-doubtful they can do that; campaigns are basically blind at this stage, and I would not be surprised if this was intentional.
Not even "native ads" embedded in LLM output can offset the difference.