The problem with BitCoin ,Ehereum and other cryptocurrencies, is that if the internet ,or power grid goes down,or an EMP occurence ,your stash is lost. But then paper money can go poof in a hyper -inflation case.
The other present weakness is the Exchanges ,where you buy and sell. Mt Gox ,which was one of the biggest was hacked and went bust,
Ther are many cryptocurrencies about.( see link) The advantage is that they can be stored on a thumb-drive and escape currency and tax controls and Govt oversight.This may change as the weak link, the Exchanges, come under pressure.
https://www.coindesk.com/coindesk-guide-worlds-national-altcoins/
The link is over 3 years old ,but may give you an idea on the progress value of each coin in the interim.