Because cryptocurrencies are an abstract idea, and ideas can always be improved, cryptocurrency's long-term value propositions will always be fundamentally weak.
The supposed purpose of using cryptocurrencies was to take advantage of a technological superiority over the traditional banking system. Ignoring the fact that the true purpose became to get rich quick, since technology is always improving, to remain logically consistent one must always upgrade to the best new tech.
This undermines the possibility of cryptocurrencies ever being a long term store of value.
Nicely done argument, but the financial Bigs have picked Bitcoin. And they rule - maybe less than before crypto, but still, plenty enough to ensure that Bitcoin remains "it".