You misunderstood.

AI can calculate stuff that can be measured and calculated.

But investing (in stocks or otherwise) is not that. Investing is about the phychology of the people (all other investors). If investors as a whole make stupid decisions, the market movements make their decisions correct (like the incredibly stupid drop in Nvidia's stock due to release of Deepseek). AI can be more objective and better at calculating facts, but it doesn't matter if the market is driven by emotions and people.