You are saying - it is not worth to use bitcoin, use fiats that are infltionary. I'm saying sell you shitty fiats and be all-in crypto like I am. Your wallet is deflationary, you are earning by simply not spending and when you want to buy someting you use crypt-fiat cards like the one from crypto.com
You don't need to hold fiats anymore.
I think we still need fiat for transactions, and regarding other things you say I agree, however the value of the currency every year will experience inflation not to mention the exchange rate of each country's currency against the USD, so saving our money in another form is true, such as crypto, stocks, real estate or any other asset that has increased in value.
I started to realize after reading some books on finance, economics, and some of them say your money will continue to decrease in value or other words, cash is a trash.
but still you need fiat for transactions, it's just that further understanding you are not advised to save large amounts of money for a long time.