Money largely gains its value from its ability to be used to pay taxes. If there is someone who controls land and an army and says "this is valuable and you have to pay a certain amount to me at certain intervals" then it is valuable, at least within that political configuration.

> Money largely gains its value from its ability to be used to pay taxes.

Even for contemporary fiat currencies today this is neither historically nor theoretically true. Currencies gain their value largely from being convenient in settling trades and being a measure of value when calculating costs, risks and profits. Ultimately, it does not really matter what this money is based on e.g. gold, paper or digital information.

For anybody interested in this perspective and in a more general criticism of fiat money I strongly recommend reading "Ethics of Money Production" by Jörg Guido Hülsmann. (1)

(1) https://books.google.de/books/about/Ethics_of_Money_Producti...

...and... where were you going with that?

Just because we made something up doesn't mean there aren't different levels of stability for that made up model, or different levels of real world results from acting on those models.

What it means is that there is no “real” justification for something to be valuable, is what people agree on. If enough people agree that crypto is valuable and want to buy it, then it is valuable for as long as people believe it is. Just like any other form of currency.