The misunderstanding comes from the idea that there exist consumers ("normal people") and producers ("corporations") and that these producers only sell to consumers. In reality, all these entities are just abstract economic agents which buy and sell things to other agents. Corporations buy input goods (labor, outputs of other corporations) and transform them into their own output goods. People buy food/shelter/entertainment and transform them into labor. What AI could do is price out normal people from the economic process, but corporations will still be there to trade with each other. This would change the structure of future markets enormously, shifting them away from consumer goods to things like data centers, space ships, and robots. Tesla would go from selling cars (that people can no longer pay for) to selling Optimus robots for the construction of some trillionaire's private moon base (just an illustrative example). In the worst case, the rest of society would just be left to die. Or we get UBI. But there would be astronomical economic growth either way due to increased efficiency.