> For that matter, what stops individuals exchanging private keys instead? This could work if you were only making transactions with people you trust, at least

> For that matter, what stops individuals exchanging private keys instead? This could work if you were only making transactions with people you trust, at least in the short term. The main risk here is anyone with the private key could transfer the contents of the wallet. The seller could even sell the same wallet to multiple people. So you need to get the blockchain involved and transfer it to a wallet that the previous seller no longer has access to.