> But we don't live in an absolutely free market, the memory manufacturers have refused to budge on creating new fabs until recently out of caution

...that's how the market works. This is called capital discipline and is standard across industries. If the increase in demand is temporary, they would be spending 5-10 years of profit on facilities which will only lose money. The same works in non-capitalist economies too, you don't want to waste resources on stranded assets and many still believe this RAM demand is temporary and the house of cards will collapse.