Food and shelter have value which is pretty near to objective. In fact it is routinely used to compare economic levels throughout history or societies. In fact it's quite useful to distinguish market price from usage (intrinsic) value. Usage value is variable from individual to individual, but there is a hierarchy of things we usually agree on, at the bottom being water, then food, then light, ... (biological stuff) then social interactions, intellectual stimulation, ... (more complex social stuff), then things like healthcare or gun access which will obviously depend on your political ethic (but which still are largely clustered, just not universal). So sure market price doesn't denote value, and intrinsic value is a fuzzy hierachy that is more and more precise given more and more assumptions on social norms, but the bottom of this hierachy is non-trivial (not everything at 0) and the top isn't that diverse.
Marx & Engels had a (critical) theory of capitalistic value where value is actually pretty well defined, as the amount of human work which has gone into something. That may be seen as an extension of what i first said (the value of human time being at least cost of life for that time).
So sure, most reasonable people would agree on food and water - but that's introducing a very very powerful new actor - your ability to judge other peoples actions as reasonable or rational. If you reserve that right - then sure, let's call crypto irrational - let's stand on the sidelines and say "well I wouldn't do that!" - let's start building the hierarchy of "reasonable values". I'm only suggesting that our ability to call someone else's valuation irrational behavior is dubious at best and aggressively violent, the birth of social engineering, the sourge of humanity, at worst (hyperbole maybe, but maybe not).
That impulse to guide "rationality" is exactly why we have modern monetary policy, and the only philosophical reason to like cryptocurrencies: a well designed, well distributed immutable ledger is more or less immune from such "guidance".
Edit: Obviously, I disagree strongly with the labor theory of value. I don't have anything handy, but there is a lot written on this (and I think the labor theory of value is fairly well demolished!). Let me know and I'd be happy to send links!
About your pick on judging other and building a hierarchy of reasonable values: well that's politics/ethics/moral (i'm no philosopher so i don't fully understand the difference between these concepts)! I'm not here saying there a is a total order between value systems, mostly a partial order based on inclusion/precision. And i'm asserting that whatever the set of living things you're taking, they'll have a non-trivial greatest lower bound (eg there is a common notion of intrinsic value) (but i think you got that).
About rationality: perhaps we don't understand the same thing by rationality but i believe one cannot be irrational, it's kinda vacuous. One can be in irrational with respect to some value system, but every one is (boundedly) rational with respect to his values (and it's by this axiom that we can infer peoples value systems). My comparison of value systems isn't on qualitative comparison between alternatives (me good you bad), it's a comparison on commonness/shared-base (this specific to me, this specific to you, this common).
on your edit: :) you feel nice to disagree with, send already, but i'm not promising i'll read! Btw i'm not sure i'll actually disagree with such critics, i personally don't really believe in value (as a homogeneous unit) because different things aren't always comparable and even different orders of magnitude of the same thing aren't always comparable (i've got no value for 0.01 house or 100 house, or more precisely it's not 0.01 resp 100 times my value for 1 house).
Many people will be selling at the same time, and suddenly the subjective value for everyone will be lower because it will be easier and easier to buy it.
My sense is that there is a cap on the demand for purchasing crypto, but the supply is very low because mining decreases over time, and generally people holding lots of crypto are younger and have no need to sell in order to pay for things, they can just pay with their fiat income.
This equation will change drastically as people start to retire and need to sell lots of crypto in order to fund their lifestyle without working.
Bitcoin slows down ensuring it's value continues to increase with fewer buyers.
Proper retirement planning means moving from 100% risky in your 20s to 50/50 in your 40s to 10/90 in your 60s.
My stuffed animal from when I was a baby has no "value", but I find it quite valuable. This isn't pendantics either - it determines more or less your entire economic perspective. If you believe in a utility or labor theory of value, of course crypto is a scam. A subjective theory? Not so much.
If someone trades an ETH for a Dollar, has value been changed? Moved around? Created? Has someone been scammed? Has wealth been created? Has net happiness been increased? Value is an extremely non-trivial thing and will lead you to love or hate the exact same situation depending on your chosen definition.
At any rate, I agree, crypto contains no value intrinsically. That said, I'm buying at the current price!
Those crypto-fans who are saying "ah well the -network- has intrinsic value" are missing the point. Value does not exist in the world. Value is like beauty or color - it's a subjective experience. All statements in the form of "X has no value" must be concatenated with "to me".
If anyone finds this incredibly interesting, and a fairly ignored part of epistemology, I strongly recommend reading Carl Menger's "The Origin of Money"