My reservation with block chains and crypto currencies: they disempower the ordinary person (or user)… instead of the Bad Guy On The Corner taking your wallet, now anyone anywhere can steal all your money, and you might not even notice it at first.
The press is reporting a $32M theft of the cryptocurrency Ethereum. Like all such thefts, they’re not a result of a cryptographic failure in the currencies, but instead a software vulnerability in the software surrounding the currency — in this case, digital wallets.
This is my concern about digital cash. The cryptography can be bulletproof, but the computer security will always be an issue.
Source: Ethereum Hacks