Why is cash king?
Not that I think that a liquidity crunch is happening right now anyways since liquidity is readily available if we judge by the Fed rates and how commited towards supporting the repo markets they seem to be. And even just the psychological effect of that strong Fed support make everyone feel safer about their liquidity levels, which makes a run for cash even less likely! Liquidity is probably the biggest self-fulfilling prophecy in Finance.
If it's living space, that's rental value right there. If it's production hardware, depends on what you produce, from which sources and how easy it is to reconfigure. Farming assets can become extremely valuable. If the asset is a stockpile of a good, again, some goods can become very valuable.
Owned land, depends, unless it's somehow prepared it's likely not useful.
Assets such as office space, hardware and supplies, not so valuable.
(But being good to your family, having low or no debt and some prudent food storage are also wise, among other things our church has counseled us for a long time). (Edit: and savings "for a rainy day".)
(Edit: This is considering the definition of "cash" to be not just paper in your hand, but as a regulated currency whether paper or in a bank. Further clarification in another reply just below.)
More generally, in times where people would rather have useful things like food, tools, and gas than pieces of paper you'll be screwed if cash is all you have - because there's going to be one hell of a price hike. Even more so because economic output is likely to go down.
Then in case the crisis gets really bad it'll turn out you can't eat cash. Nobody is going to hand over food or other useful things in exchange for a few bits of paper with questionable value.
This may be happening in some limited fashion even in the current crisis. My country still has its own currency within EU, and is undergoing unprecedented levels of lockdown over the last few days. The currency is already tanking compared to Euro (lost 4% over a few days), as people stockpile stuff.
Cash is filthy bacteria rags that are pure liquidity. Contactless and Cashless solutions are the future.
You're missing an important piece of the puzzle. People want to trade for something that they perceive to have more value than the thing they are trading. This can't work if you have an infinite dollar printer (or magic numbers somewhere on the internet) because the money will be perceived as worthless (or will become worthless in the not so distant future).
The future is being able to trade something which is perceived as holding (or accruing) value which can't be arbitrarily reduced by policy-makers, and also is highly liquid, difficult to forge, easy to verify, low-cost to transact, and can be used as payment for most services. Any guesses as to what this might be?