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I am pretty much this was because of fat fingers, but how an earth there's no security measures for this kind of thing? It's 2020 already and after seeing this kind of mistakes, i am pretty sure that ETH adoption is further away. Just one warning message informing about the possible huge mistake could have saved millions for this guy.
It is really unfortunate and sad to see these kind of mistakes and this is not the first time i am seeing these mistakes while sending the coins but this is by far the biggest mistake i have seen. Not sure what can be done to retrieve his coins, not sure whether the miners will do the logical outcome in a situation like these as the amount here is 10,668 ETH and it is suicide to mess the gas price and let go off his wealth because of a silly mistake.
No one would reverse the chain just for some thousand ETH sent mistakenly.
This is both the beauty and risk with the blockchain platforms that there's no correction once the transaction has been broadcasted. Though I too believe every wallet should integrate some feature to warn users when they are trying to make some out of the ordinary fees transactions.