James Demmert, Chief Investment Officer of Main Street Research, warns that the current bull run in the stock market, driven by FOMO and AI hype, may not be sustainable. He advises investors to be patient and use any corrections as a buying opportunity. He also anticipates that the Federal Reserve might take a tougher approach at its policy meeting, which could lower stock prices. Furthermore, he suggests that upcoming earnings reports from big tech companies like Alphabet, Meta, and Microsoft could weaken the AI sector.