Do not trash Fiat yourself when it's actually needy, crypto and Fiat must co-exists until the government decide to go digital with Fiat themselves, and Fiat is not trash.
You made an interesting point that fiat and crypto should co-exist which in my view is very practical approach. Fiat has been in use as method of payment since decades hence, it will take time before people start accepting new forms of payment. Generally people refer fiat as "trash" in the context of its consistently decreasing value which reduces our purchasing power and it becomes difficult to afford basic needs of life.