Same as the big tech companies, probably make all of their products worse in service to advertising. AI-generated advertising prompted by personal data could be extremely good at getting people to buy things if tuned appropriately.

Well. If you're using AI instead of a search engine, they could make the AI respond with product placement more or less subtle.

But if you're using AI for example to generate code as an aid in programming, how's that going to work? Or any other generative thing, like making images, 3d models, music, articles or documents... I can't imagine inserting ads into those would not destroy the usefulness instantly.

My guess is they don't know themselves. The plan is to get market shre now, and figure it out later. Which may or may not turn out well.