Banking is good for the economy because it makes sure to balance out all of the money. With that being said, take for example what happens when you put money into a bank. When you put in money it sits there, when other people withdraws money, the bank sometimes uses yours to balance out the banks total. That is how you collect interest, which is where they pay you to use their bank and pay you for letting them use your money without ever messing with the amount. That helps the economy by everyone having at least some share of money. It also helps the economy to flow and makes everything a little easier. Hopefully this helps you in getting the answer you asked.