This is a quote from the book "On Zero Confirmation Transactions" by Chris Pacia
... arguments like “only the blockchain can prevent double spends, that’s why we have it”. Of course, but notice that we aren’t talking about preventing double spends, only detecting them. And in the six years bitcoin has been going, this risk mitigation strategy has worked fairly well. Most bitcoin purchases are done through payment processors who accept zero confirmation payment s and the rate of fraud has been negligible.

This doesn’t mean every double spend attempt has been stopped, they haven’t. But we don’t need to stop 100% of double spends ― o...
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