The problem with this hype cycle has always been that the hyperscalers are pouring unbelievable amounts of capital into a technology that hasn't proven it can generate the revenues needed to justify that.

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).

This exactly. How sustainable are the current spends in the wake of needing ROI against these spends in the not too distant future? And who will be able to afford an upgrade cycle only 2-3 years from now given none of the capex spent will have hit positive ROI 2-3 years out.

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.