Nontrivial markets don't behave like Economics 101 textbook examples.

Samsung, SK Hynix, and Micron have a combined market share of 90% - with most of the rest being a very new-to-the-market CXMT. It is a cutthroat market which behaves like a stereotypical "pork cycle". Semiconductor fabs cost billions to build and take years to complete, so you better be damn sure you have buyers before you start constructing one. You and your competition overestimated the demand? You have to pay back the construction cost, so you're now in a race to the bottom and one of you is going bankrupt.

Ever wondered where Intel came from? They started out as a DRAM manufacturer, which dominated their revenue well after the introduction of their first microprocessors. But in the early 1980s the glut of supply from new Japanese manufacturers made it so unprofitable that they had to ditch the memory market altogether. The stories of Texas Instruments and Motorola aren't much different. And that's not even mentioning the likes of Mostek, which once held a 85% market share and was dead less than 5 years later! Oh, and those Japanese manufacturers? All gone, pivoted like Intel or died like Mostek.

So no, the three remaining DRAM manufacturers aren't going behave like headless chickens and start ordering new fabs just because there's a bubble causing a temporary demand peak. Unless those AI companies are going to pay in advance, in cash, for an entire fab, they'll just have to wait and deal with the price increase.