Yes but I would argue that there is a large disparity between the fiat currencies used to purchase BTCs vs the fiat currencies that are purchased when selling BTCs. I cannot find an older article I read on the topic, but essentially a larger portion of non-USD$ are used to purchase BTCs then are re-purchased when selling BTCs with the disparity being made up of purchased USD$ (if that made any sense).

Just making up numbers: 50% of all purchases of BTCs are made with non-USD$ fiat currencies. But 75% of fiat currencies purchases with BTCs are USD$.

People are using BTCs as a transitory vessel of value to realize gains made on one side of the swap. And the gains are made concrete by purchasing USD$.