The current overall shortage in the wider ecosystem is not even limited to top-of-line 5nm parts, but the fundamental issue of "you can't just spin up a fab" remains of course.
Why not?
I mean... look at the current plague pandemic - we've been listening that you cannot just create more space in hospitals overnight, or build new rooms, and this and that... but it's not overnight... it's been a year now, and if they started building the first time they said "it cannot be done overnight", we'd have a lot of nice empty rooms now.
I remember waiting for some parts in 2002, that were delayed due to many stupid logistic issues in Korea (fifa world cup was there, then), and the excuse was the same... you cannot just make more factories overnight. Graphics card prices are overinflated, ram prices are inflated, ssd prices are inflated.... basically, anyone who starts building any form of production now, will be able to sell whatever the company puts out without issues.
I know I might sound like a conspiracy theorist, but there is either some cartel deal between huge companies (intel, amd, nvidia, qualcomm,...), to keep prices artificially high and blame parts shortage, or they're all incompetent.
https://en.wikipedia.org/wiki/Semiconductor_device_fabricati...
There is a table on the right, and there are rougly 2-3 years between 'generations' - so 2-3 years between starting a new production line of top-of-the-line flagship (eg.) cpus, to making a new production line for even newer, "smaller" (transitors) cpus, and the old line making other, cheaper ones.
I'm not saying that Johnny Sixpack can do it in his garage, but companies like Intel, AMD, samsung, etc. surely could do it in that timeframe, because they're already doing it now.
In the end, making chips just isn't that high on the overall list of things to be able to opt.out of normal market forces. If it looks like customers will pay enough to make rapid expansion and the changes necessary to enable such rapid expansion worth it, it'll happen.
But demand is not actually that much higher than normal, and thus the investment has limits. You can be sure that everyone is working to finish their expansions as fast as possible (hundreds of billions of investment over the next few years) and get their broken-down fabs back online ASAP, but its not like they suddenly can spend massively more resources on it. Compared to big challenges like fighting COVID its overall a minor concern, and as you point out even that did not go as all-out as it could have.
A semiconductor fab typically needs several of these machines (maybe only one or two of the best machines for the smallest layers, but more of the coarser machines for the less dense layers) in order to produce chips competitively.
So here's what actually happened. Car companies cancelled their orders because there was this thing called COVID. Those slots on fabs got sold to other people in the entertainment industry because at the time it was believed people would just stay at home and the entertainment sector would need the extra fabs.
In a sudden twist of what could be called "irony", it turns out people are scared of getting on public transit during and after covid so everyone who relied on that or uber/lyft started buying cars so demand for cars went up. Car companies tried buying their slots back kicking off a giant demand hike which basically had people buying fab slots for far more than they are worth... the issue is that those ICs aren't like a graphics card.
If you don't have 5nm chips, well that's fine, you can't produce a graphics card per IC, for a car, there could be dozens of different chips. If your 30nm chips are out of stock, it doesn't matter how many 105nm chips you have in stock, you can't sell half of a car.