“But there’s a store of value you are ignoring.”
Do tell, what is the underlying asset that has value? Debt? Precious metals? Salt?
There are several components to the value. One is relative permanence. The caveat is that the PKI will be brute-forced in 60 years maximum, with no new advances in cryptoanalysis, only the normal progression of computing power. So it is doomed at that point or earlier, but "permanent" until then. Second value is aesthetics which is why there are new CC all the time (alt-coin bubble is just getting started). Some new currencies have the advantage of extending the "permanence". Those that truly do (not just hype) will be much more valuable.
Third is the utility of digital currency in a digital world. I can purchase purely digital assets through a purely digital transaction which is not possible with any other currency. Fourth is how easy it is to keep from losing your asset. The physical assets you mention, PMs and salt, can be stolen. The debt or obligations can unwind in an economic collapse of a country. All of your mentioned assets can be easily (trivially) confiscated by the authorities. By owning a private key there are 1000 ways to get your value out some shithole (the usual ones or the ones created by Dem takeover) to somewhere where the CC is still valued. A worldwide synchronous collapse negates that value along with a lot of other asset classes.
Finally you are asking the wrong question. What is the underlying value of a bunch of splattered paint on a canvas? What is the underlying value of an open source software product that everyone can download for free? What is the value of a simple worldwide pure digital asset network? Obviously zero, in your narrow view.