It would take another massive hacking to derail cryptos. Unfortunately, recent history is replete with big failures in crypto security. E.g., Mt. Gox hack, Poloniex hack, DAO hack and most recently, Freewallet hack.

https://steemit.com/ethereum/@hoyareb/usd8-million-in-cryptocurrency-ethereum-stolen-from-freewallet-scam-or-hack