Bitcoin has also done this.
You're referring to the $50m DAO smart contract bug (or "hack") early in 2016, when Ethereum had been running for about a year. The Ethereum blockchain was swiftly rolled back. This was achieved by the majority of Ethereum developers agreeing to create an update to Ethereum software that reversed the hackers transactions specifically, and the great majority of users and miners agreeing to use that updated software. The people behind the DAO were closely connected to the Ethereum developers. Some of them were Ethereum developers. Some of the people who lost money in the DAO were Ethereum developers.
What you're unaware of apparently, is that when Bitcoin had been running for about a year, in 2010, a bug allowed someone to create 184 billion Bitcoins. This effectively made everybody's Bitcoins worthless (or even more worthless!). This event was ALSO swiftly rolled back, just like the Ethereum DAO event, by the same consensus process that I described above.
"Core developers Gavin Andresen and Satoshi Nakamoto were on the case, and the 184 billion BTC transaction was purged from block 74638."
https://news.bitcoin.com/bitcoin-history-part-10-the-184-bil...
Since then, there have been various incidents involving Ethereum and Bitcoin and hacks or smart contract bugs that caused losses of millions or billions. But neither currency has ever done a roll back of this nature again.
For instance. A year or so after Ethereum's DAO debacle, there was another similar event, the Parity bug, which accidentally locked $230m in a smart contract, permanently. The people operating Parity were closely connected to the Ethereum developers, some of them were Ethereum developers. But this time, although the victims pleaded for a roll back, it was never seriously considered.
https://news.bitcoin.com/parity-calls-for-ethereum-hard-fork...