Although they are non-inflationary currencies, they remain volatile. You can have variations of several hundred dollars or euros in one day.
Investing in crypto-currencies turns out to be sporty. In any case, it is not Zen compared to Air Liquide. Admittedly, the comparison is exaggerated but real.
The volatility of crypto-currencies can be attributed by:
Low listing history
Central banks can not create them themselves
Investor craze for immediate gain
The media self-sustain this craze
(The financial elites will use the weapon of regulation and taxation, and could secretly create scandals about virtual currencies, to put public opinion in their pockets.
For example, China, which ended the ride of the ICO (crypto-currencies), is about to test its own national cryptocurrency. She plans to back it to the Renminbi. If so, it will be a major breakthrough for the cryptocurrency world.)