See:
There Is No Escaping History. Fiat Currency Eventually Fails.
Notice that this is a critique of fiat money -- not a critique of state-issued money under a gold/silver or other standard. Fiat money is a rare occurrence in modern history. (We live in strange times!) As we can see, the examples found by the author are a small number of short periods here and there.
I have my own critique of gold/silver standards, but that's another issue.
This is true but the big problem here is not that fiat currency fails but the terrible effects it has in the economy in general and in the economy of each person, when the fiat currency fails it tends to sink the country and everyone becomes poorer because of it and then you need to trust that the government is going to finally get it right when they issue a new currency.
Fiat currency is helping us in different ways of life or life activities so we can not neglect its value and role therefore fiat is strong and we will have it through out our life.
We can invest in the most popular and powerful fiat as well like dollar besides this cryptocurrency has catch the sight of investors as it is a huge profitable source and diversifying investment is also a good strategy so most investors follow this strategy.