You forgot to mention using of customers money to give out loan to buy loan to well know companies that'll pay them back with interest. Banks don't keep all the money deposited with them in their vault. They lend it out for people to use in doing business. They also borrow the money and invest in forex, real estate and other businesses that'll bring profits to them.

Banks are the wealthiest organization because they control money and money is the most important thing on earth as everyone that has it is in power. Banks have other means which to get money illegally. When their customers dies and no next of kin, they take the money.