Fiat has an intrinsic value, in that it can extinguish your tax liabilities. Come April 15th, it doesn't matter whether your income is in bitcoins or onions or beanie babies, you will have to acquire USD somehow to pay the IRS their share.
Could it be argued that crypto has intrinsic value in it's ability to hide from these tax liabilities? I've seen Bitcoin, and other crypto-currencies, compared to the off-shore tax evasion market, as it seems to be able to fulfil much the same purpose.
Of course, Bitcoin as a vehicle for tax evasion isn't a good brand, unless you're very libertarian.
Everyone needs to pay taxes if they don't want to have the police kick in their door and drag them off to prison. Most people don't have an unavoidable need to evade taxes.
Using bitcoin to move around assets and evade taxes presuposes that it has a value. It cannot be an explanation for the value of bitcoin. As we've seen from all the altcoins and bitcoin forks, crypto-"currency" tokens are not exactly a scarce resource. You can create an infinite variants of them, or an infinite copies(forks) of the same blockchain. There is no fundamental reason(i.e. you can't tell just by looking at the properties of the token) why Coin A exchanges for more USD than Coin B.
Some of these tokens can have some intrinsic value, when the coin is set up in such a way that you can "redeem" them for computation time, data storage, content etc. Then it functions in a way similar to an accounting or point system. But beyond this, the price of cryptocurrency tokens is propped up by nothing more than speculation.
https://en.wikipedia.org/wiki/Chartalism