A calculated move. If they're right and the AI demand is a fluke, they don't overinvest in expensive manufacturing infra, they don't get saddled with more capacity than they need, and there is no memory glut eating their margins in the future. If they're wrong and the AI demand isn't a fluke, they get to pad their margins big time, and the supply bottleneck isn't their problem. As long as they shake hands and bet on "fluke" in sync, the downside is very limited for all of them.
They shook hands, they bet in sync, and they were wrong. Now the supply bottleneck is everyone's problem.
Potentially even theirs - if Chinese vendors can use it to wedge themselves into the market when it's at its most lucrative, and invest in growth. Which they almost certainly will.