The question the memory manufacturers have is, sure, we have all these orders out to the next three years... but will they actually be there to pay when the memory is delivered?

The memory manufacturers have been through bubbles before.

I don't deny that AI is "real", in that there is certainly something there, but I would hate to be the guy betting billions or even trillions of dollars that we're not in a demand bubble well in excess of what is justified by that tech at the moment and expanding capacity is a great idea. Of course, I would also hate to be the guy saying "no we shouldn't expand capacity" when it turns out that, yes, we should have, but the staggering profits being made in the meantime would cushion that blow pretty well.