> This, in the end, could cause a big loss to some user of the exchange Not really. If someone is worried about a double spend attack, all they have to do is

> This, in the end, could cause a big loss to some user of the exchange Not really. If someone is worried about a double spend attack, all they have to do is require a larger number of confirmations, until they are satisfied with the amount of security, for the given value of the transaction that they are accepting. For example, if a big exchange is accepting a million dollars worth of crypto, they might want to wait a very long time, in order to be absolutely sure. If someone is instead accepting payment for coffee, they could be perfectly happy to accept more risk.