Double Spending before confirmation What&#39;s to prevent someone from using bitcoin at a store like subway and double spending to buy the sandwich before a confirmation is made? Since subway obviously isn&#39;t going to wait for a confirmation, can&#39;t a person send bitcoin to subway and at the same time send that bitcoin to another address?
RBF exploits are possible for 0 confirmation transactions.

The risk/reward is tiny so some merchants will accept small transactions and make delivery without waiting for a confirmation first.

99.9% of the people who have both the competence and lack of morality to double spend in this manner would not waste their time on such a low value theft.

All merchants should wait for (at least) 1 confirmation of possible but the risk is too small for many people to care when selling sandwiches. Any merchant selling a yacht should be waiting for multiple confirmations anyway so the RBF exploit should not be relevant for high value transactions.