In a world where people lived within their means, Visa and its competitors would not exist. But with a market valuation of about $133 billion, and profit margins at 42%, Visa proves that extending credit to consumers and assuming they’ll be irresponsible is a gainful industry.Visa’s primary business entails allowing financial institutions to distribute cards bearing its brand name to account holders, and charging merchants for the right to accept Visa. For example, Bank X provides Visa cards to account holders, enabling them to shop around and make purchases without carrying wads of cash. But using a credit card instead of actual cash makes it harder to keep track of your spending, and thus likelier to buy more than you would using cash. So Bank X charges interest, and Visa profits. When a merchant signs on to accept Visa cards, it pays up to 3% of each transaction to Bank X, which has paid Visa for the right to use its network. Merchants know it’s better to pay that 3% and receive 97% of each transaction than to refuse credit cards and lose customers to competitors who accept them. Visa’s technological prowess is extraordinary. It processes more than a billion transactions a week. Visa obtains a piece of every authorization and settlement, and charges for the access to its worldwide network. The bottom line is Visa is selling personal convenience with a price. Consumers who pay off their Visa bill each month force financial institutions to pay to accommodate them. But consumers who maintain a monthly credit card balance contribute to a scenario that helps Visa profit handsomely.