True for small transactions, however...

With Bitcoin at $1 it would be impossible to transfer $22 million in value, because there aren't enough bitcoins. The higher value bitcoin is in fiat, the larger a transaction can be.

Another example: a wealthy person wants to store $22 million or more of their wealth in bitcoin. Couldn't be done with bitcoin at $1. The higher value bitcoin is in fiat, the more wealth we can store in bitcoin.

Same thing for 22 million people each trying to store $1 of wealth in bitcoin.  Or 220 million people trying to store $0.1 of wealth in bitcoin, etc. Couldn't be done with bitcoin at $1.

The utility of bitcoin to the world as a whole rises as its fiat value per coin rises.  We need bitcoins to be worth a lot (say $100k to $1m+) per coin to be useful to the world's population because there are so few coins (only ever 21 million will be made).