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claim the lost deposit at poloniex. because we did nothing wrong. (right memo, right adress)

Not sure if we can do something like that. We've transferred the money to poloniex and now they own the money :[

But if we cant restore it, what is the steemit blockchain worth?

You can say the same thing about every other blockchain. Once the money is out of your wallet, it's out. It no longer belongs to you! :[