Maybe the problem is a lot of their marketing relies on the dominance of their search engine (ie sponsored search results, and ads based on user searches, as well as tracking user web usage via their search click throughs and other cookies). If open ai's products become the go to for questions and basic searches, they will eventually be able to use that dominance to include marketing results in their answers. I think this threat is why they want to try to compete with them to be able to offer an alternative. Because it doesn't actually have to be better than chat gpt. It just has to be similar enough for people to continue using Google rather than change their habits to use chatgpt, or Microsoft's implementations of it. Especially with windows 11 where copilot (basically Microsoft rebrand of chatgpt) is built in and you can use it from the task bar. That ease of use may steadily decrease people's reliance on Google search, which will eventually hurt their ability to sell targeted ads.