Cryptocurrency is just a financial market and to exist it needs investors and investors need fiat to invest to drive the market
Again, bitcoin(satoshi) didn't need investors from the start, it needs Hal as a adopters/contributors/users. In conclusion, bitcoin needs more people like Hal Finney.
And that's what I said that users can't migrate completely from conventional systems because one of the reasons is long-standing dependency. Fiat is only a standard for assessing all entities and activities that have unconsciously become common practice.
Bitcoin can actually also value goods and work relatively, a simple example in a small scope (points for @n00ber also how to invest in bitcoin without fiat without a bank): Almost all campaigns run by @icopress in the service section give a standard flat value for each post is B0. 00008 ~ B0.0001 (ignoring fluctuations). Anyone who doesn't mind can take it. If all managers, sellers of goods and services on this forum implemented the same thing, then slowly the reference standard value on this forum specifically would become only bitcoin.
Bitcoin is not free and we need money to own it and how do you use bitcoins for everyday payments if you don't convert them to fiat?
I accumulated my own bitcoins from the signature campaign and some past jobs. I didn't ever invest into bitcoin with even a cent), if regulations doesn't prohibit me from buying all my necessities with bitcoins and local shops accepted bitcoins, I'd do it as needed.