In the days of old people used to trade and barter things. People would swap a pig for a goat, a bag of wheat for some chickens, a "magic" stick for all their worldly possessions (for the people of old were very superstitious). This would ultimately lead to massive arguments over the relative values of each of these things against the others. Thus, some clever bloke along the way came up with the idea of money. This person obviously already had the idea of a bank in motion at this point, and thus the concepts of virtual wealth and dubious moral values were born.
The bank is a rather curious concept where people give their money to an organisation that invest it wisely thus making money for themselves, but return only fractions of the proceeds to the customer in the form of interest payments. However, banks do have their advantages: they allow someone to keep money securely; they can lend money; they can purchase and exchange foreign currency; and they can make one feel amazingly inferior, if that's your sort of thing.
The first of those points is actually rather good - instead of hiding money under the bed, in a drawer, or in your pants, you can sleep safe in the knowledge that your money is safe and sound. Even if a bank is robbed, you'll still be able to get your money back, and the cases of entire banking corporations going bankrupt themselves are incredibly rare, at least in the western world.
The remaining points, however, are less advantageous, and usually the bank is making money from you in a rather sneaky manner. The most obvious of these is when buying or selling foreign currency - not only will the bank offer an exchange rate that is advantageous to them, they will also charge a "commission" rate. Note, that is often not possible to exchange less than the equivalent of five pounds because you'd actually have to pay the bank for the privilege!
One recent phenomenon that has made people shine more to banks is that they allow customers to get at their money through a "hole in the wall". Note that these aren't really actual holes in actual walls, but machines that dispense money after one inserts a plastic card. However, a bank's philosophy is thus: that if you should be so privileged as to receive one of these beautiful cashcards then you should take care of it much more than, say, a very expensive digital watch.