Thousands of people had come from outside towns and far countries. They had to purchase oxen, sheep and doves for their sacrifice. They had to exchange their money for temple money, which was the only legal money that could be offered to God. It was dishonesty that annoyed Jesus. Much confusion arises from imprecise definitions.
Words can have many meanings depending on the context and times in which they are written.
Modern credit-money are contracts denominated in units of account, which represent a shared consensus as to value. Credit-money therefore derives from transactions in trade, and cannot be quantified as a scarce commodity. You take your personally executed IOU in the form of a promissory note to the bank, which exchanges it for the bank's IOUs in the form of deposits, which are more readily acceptable to the community. Increasing trade and commerce is thereby facilitated. The banker is justified in requiring compensation for the service he provides.