The difference between the USD and BTC isn't that one loses value every single year and the other doesn't. It's that one is actively managed to ensure it retains ~98% of its purchasing power over the course of the year and the other isn't.
That 2% fall really isn't such a huge deal for people that want instant access to the only money their creditors are required to accept, the only money they can pay their taxes in and the only money that's widely accepted elsewhere. (Other assets might actually gain purchasing power more often than not, but can also fall relative to that impending tax bill)
Most of the world's wealth is stored in assets which are not money or bank accounts anyway. And if people want to hold all their savings in something with a better return than their bank account, then bonds and stocks have been around, fungible and convertible to cash via apps for a very long time and payment app-ized versions of those are a far more plausible alternative to traditional banking for the average person than intrinsically worthless cryptographic signatures "mined" in China and shilled for on forums. The only thing unique about cryptocurrency as an economic asset is that it has no legal tender status and zero income stream, rights or assets attached to it. There might have been people orchestrating surges and crashes, but that's pretty much the best case scenario for assets which people have no reason to value at all.