Just as any other card issuer, they should be getting something like 1%-2% (depending on location and merchant type and card type) from all purchases as interch

Just as any other card issuer, they should be getting something like 1%-2% (depending on location and merchant type and card type) from all purchases as interchange fee from the merchant. Assuming their processing infrastructure is efficient enough, that should cover all the expenses and allow for some profit even for customers with small turnover.