In the same way if you housed all your gold in your house and your house was robbed, you'd go from a possible millionaire to less than a millionaire too.
Personally, I wonder if cyrptocurrencies will ever replace fiat currency because of how people treat them. They're treated much more like stocks than anything, and their value is so volatile that it would be very difficult to accurately pay for items using them.
I understand all currencies fluctuate in value, however you don't see the US dollar loosing 25% of its value in a day. And if it did? Well, people would be rioting in the streets.
That's the reason why USD doesn't fluctuate:
http://money.visualcapitalist.com/worlds-money-markets-one-visualization-2017/
When you fall from the rooftop no one sees that earth is also moving toward you! They only see that you're falling!!