Are crypto currencies fiat currencies?

I have heard for years from analysts to get out of fiat currencies, in the last 6 months we have heard a frenzy of people saying get into crypto currencies. The problem I have is that crypto currencies are a form of fiat currencies. Lets have a look shall we?

noun

an authoritative decree, sanction, or order:
a royal fiat.
Synonyms: authorization, directive, ruling, mandate, diktat, ukase.

What is fiat currency? Investopedia helps us.

What is 'Fiat Money'
Fiat money is currency that a government has declared to be legal tender, but it is not backed by a physical commodity. The value of fiat money is derived from the relationship between supply and demand rather than the value of the material that the money is made of. Historically, most currencies were based on physical commodities such as gold or silver, but fiat money is based solely on the faith and credit of the economy.

Now lets investigate crypto currency. As of right now I think there are 800 different crypto currencies. The most widely known is bitcoin. Anyone can create a crypto currency, obviously since there are so many of them. What is backing them? Faith! Faith and trust that it has value. That is it. Nothing more. So, someone creates a crypto currency OUT THIN AIR, says it has value in hopes others will see value in it also.
So, we can see crypto currencies are indeed a fiat currency with nothing, ZERO backing them.
Why in the world would someone want to go from one fiat currency to another? Especially when faith can be lost and they can come down as fast as these are rising. I just do not get it.
I suppose if you wanted to speculate on them to ride the wave up and sell at the top, good for you to pocket some cash. But to hold them in the place of gold and silver as a store of wealth? In my oppinion, very risky. Just as risky as holding fiat dollars.