What public company is massively overvalued in your opinion? Nvidia right now is trading at 44 P/E which is higher than the S&P average, sure, but not anything like the dotcom bubble with a median of 120x earnings.
Nvidia might have an ok P/E right now, but the question is if the industry can sustain buying over $50B of GPUs every quarter(or that it even needs to).
Will everyone just accept negative ROI in the name of hype? Will scalers be able to meaningfully increase service prices without eroding customer interest?
These are all unanswered questions that a simple PE statement can't support.