Banks naturally believe in keeping all the money.
Turning customers into millionaires just isn't part of their make-up. Customers are supposed to deposit their money and then leave, so the banks can then use the money for lucrative overnighters that don't show up on the balance sheet. Plus, they can even charge their customers for using their banks. And bankers have always resented the fact that a single stockbroker sitting at a dreary little desk will usually have more money under management than most banks, with all their hoopla and decorum, will ever dream of having. If not, he's out of business.