Many people do not understand that fiat do not hold any value anymore. It always go down. Always. And now it happen much more than most of us ever experienced in our lives. In recent times inflation is highest since decades and it is just the beginning.
Before covid, few years ago it was rational to hold fiat and not be all in crypto. With inflation 1.5% or 2% yearly it was still rational decision to diversify and save some money. But it was before 2019 and is not actual info anymore. It was before covid, before huge inflation and printing of few trillions $. Over $4 trillion printed in just 2020.
Current USA inflation is 6,8% and it is highest number since 1982
Current inflation in Venezuela is around 2700%, your money are literally worth less than paper they are printed on
Current inflation in Argentina: 52%, you would lose half of your savings in just one year
Current inflation Germany is almost 6% and is highest since 1992
Current inflation in France: 3% highest in 10 years
Current inflation in Lebanon 174%
People that hold large amount of fiat are simmilar to patients that don't want medical treatment cause it can possibly make their condition worse. But they don't understand they will never be healthy without treatment. They need to risk to save themselves or in long term they will lose everything anyway.
Holding fiat is really dangerous. I do not tell invest all in crypto, but at least buy things that hold value ( furnitures, land, gold & silver), invest in stocks or at least spend those money on things you enjoy: like travels, when they still are worth more than toilet paper. Saving fiat is worst thing anyone can do. Have small emergency fund, but remember richest people do not hold much fiat. They know it mean losing money. All their money are invested into some assets to increase in value not decrease.
Crypto unlike fiat at least give you chance to have profits. Crypto can possibly go down, but I will trust all my money BTC or other good project much more than I would ever trust them USD or any other fiat. Cause crypto can also go up a lot. And chances for crypto going up are actually very big if you chose solid projects. Fiat will never go up, only down. Your fiat become worthless in few years anyway, chose wisely how you want to prevent it.
Tl;dr Litterally everything is safer than holding Fiat.