You shouldn't be using any currency as a long-term store of value. Even if you want to be denominated in USD and minimize risk, the interest rate on cash in a mattress is zero and the interest rate on US treasuries is non-zero.

Meanwhile the historical purpose of holding cash as "spending money" (i.e. liquid assets) is from a time before computers could allow you to keep it as actual investments until the instant you do actually want to spend it.

As for using it for pricing, things are typically priced in USD because it's the world reserve currency, or in the dominant local currency in a given country. That doesn't mean that other currencies aren't currencies. Shops in many countries will often accept both local currency and USD even if prices are only listed in one of those, and so what? Anybody can look up the current exchange rate in real time on the internet. Why is it a problem to list prices in USD and then accept that amount of cryptocurrency (or Euros or Yen) at the current exchange rate?