The biggest bitcoin failures in terms of lost revenue have been due to hacks and mismanagement at the exchanges. Since blockchain itself is secure from tampering, malicious people have chosen to attack the institutions that deal with cryptocurrency. Other failures were just scams designed to swindle people. Although the scammers didn’t always get away with a lot, such activities can still be counted as failures to the virtual currencies.
There are very many such failures to list in just one post, but we’re going to highlight the most prominent ones.