Starting with what money is takes the conversation off price, and that is the right move. What keeps the sale at zero is rarely volatility. A Lightning payment settles in seconds, so his coins are exposed for a minute at most. The barrier sits earlier: he has to own bitcoin before he can hand you any. Scanning a QR to a website is the weakest link in that. A man who just had his first real thought about money will not rebuild it at home from a link. Price one jar in sats and the QR gets used while he is still standing there.