Do we have evidence that this will actually happen? Maybe the belief that it won't pass is what requires evidence, but I think there's a widespread feeling right now that things are just getting permanently worse and this is one example.
People do that all the time, and sometimes it doesn't pay off.
One thing holding back capacity expansion is that a lot of people are concerned this is a bubble. They're worried it'll pop and leave them with orphaned assets if they over-invest in production.
Of course maybe they're right and that will happen. If the data center construction boom ends, RAM prices will fall.