A lot of people seem to have learned economics 101 but not control theory, and seem to think that the economy will respond to signals instantly rather than having a finite frequency response.
The high level of uncertainty doesn't help; how sure are you that there won't be a pandemic related demand crash in six months?
In past shortages, that demand crash is precisely what happened. Considering how long a new fab takes to pay for itself, and how thin the margins are in fabbing trailing-edge chips that have been around for years, it would be a major risk to lay out more capex than your road map from 2019 suggested. Meanwhile, if you just keep doing what you're already doing, utilization is high and prices are rising so you're guaranteed to turn a rewarding profit. There's not a major private-sector incentive that would justify costs whose amortization would require consistent demand for several years.
The high level of uncertainty doesn't help; how sure are you that there won't be a pandemic related demand crash in six months?