Cryptocurrency is a token like Chuck E Cheese coins or Beer Garden tickets - they are only fungible in certain venues that explicitly support them. Obviously, even if 4x Beer Garden tickets are equal to a dollar, their purchasing power is not the same. Beer tokens buy one thing, and to be meaningfully fungible in other contexts they need to be liquid first. Cryptocurrency (even stablecoins) operate on the same principles. They will always be inferior to the dollar purely on the virtue that they rely on the value of $USD to exist.
Even the peer-to-peer usage is primarily driven by enthusiasts and spot-traders. Cryptocurrency's only future is being treated like ERC-20 Pokemon cards.