Nvidia and Microsoft correctly bet on AI years ago by heavily investing in AI research and development, propelling them to become the world's top companies in terms of market value above Apple. Nvidia's focus on AI chips under CEO Jensen Huang and Microsoft's investment in AI companies like OpenAI have paid off amid the recent AI boom. There is uncertainty around how long the AI boom will last as not all AI technologies have lived up to the hype and some stocks focused on AI have fallen this year. The future of which companies remain at the top depends on who can best navigate the uncertainties in the AI field and show continued meaningful growth.