The AI boom created lofty PEs. A ton of money made from capital inflow will get blown on chip fabs to drive their street narratives. The chip fabs will result in oversupply, the basic nature of fab economics. Net $ earned will be not much.
The general S&P might get a few % productivity from GenAI over a few years, that's all.
Its going to play out a lot like the DWDM telecom boom bust