Even if they hold the same opinion as Micron’s CEO, spinning up such a fab to reasonable yields would take a couple of years.
It’s a known dilemma in farming. Your crops are losing, so you decide to switch them to crops that are profitable, but so do your six neighbors and by the time the new crops start producing, you have flooded the market and everyone’s losing again.
Which is a huge problem for a farmer who redirected 100% of their capital to a new crop that turns out to be unprofitable. Whereas if you do that with 5% of your capital and it doesn't work out, you shrug and hardly notice. But if it does work out, that 5% is now worth 20%.