The Parity team is one of the most respected in the entire Ethereum ecosystem. Led by Gavin Wood, one of the founders of Ethereum, they are some of the most experienced and skilled blockchain developers in the world. Unfortunately, everyone is human and the Parity wallet product had a flaw. This flaw allowed an attacker to drain wallets remotely, resulting in millions of dollars of ether being stolen. Thankfully, the attack was not automated, which gave the ecosystem time to notice and respond.

The flaw was fixed, but the fix itself created a new bug. This bug allowed a new attacker to issue a kill command to the wallet, freezing all funds. As of the time of writing, over $260 million in ether remains locked. The community is still trying to figure out a way to rescue the funds.

The moral of the story with the Parity wallet hacks is that even the best teams can make mistakes and that it's vital that any code on Ethereum has some sort of upgrade path. It's also clear that until the ecosystem improves, any code running on Ethereum should be seen as risky. If even the founders aren't perfect, that should tell you the difficulty involved in doing it right.