In a stable economy like the USA, companies are not PRICING products in bitcoin, they are converting to USD at the moment of sale.
Do you have a proof for that? I've sent a lot of bitcoin to heaps of merchants, most of which live in "stable" economies like the US, EU, UK, and I'm sure lots of them don't choose to exchange their bitcoin for fiat. I can look into the chain and confirm it for you, but that'd be just a waste of time. You deliberately avoid to understand it.
But if Bitcoin has to be compared to the absolute most worthless, unstable FIAT currencies in the world
Every fiat currency is potentially worthless and unstable. See Russia; strong economy, but
shitcoin. USD is now more rapidly decreasing in value, and so is EUR and GBP. Every nation on Earth is currently experiencing massive inflation, because those who're responsible for the economy cannot be trusted to maintain it, and there are only the willingly ignorant fools like you who can't see the benefits of bitcoin.
Μeanwhile, bitcoin rises by about 180% since the first halving, on average. Probably nothing.