What are the advantages of a banking sector in an economy?

Banks today have a lot of investment in many areas. They give car loans so if more cars are sold they make money. They sell insurance so with more cars more insurance is needed and they invest in housing so they also sell the insurance for houses. They also have the mortgage industry and make money when a loan for a house is made. They loan companies money to business and make money off the interest they charge. If you use a credit card you are making a loan from a bank. Have a checking account and they charge for the account and charge for a overdraft of money in the account. Use a ATM there is a fee. All of this money goes back into the economy in some way.