an uncle that worked too long on banks used to tell that when he started, he would be writing mainframes applications to calculate the 'cost' of a client for the bank. Basically, the bank would give the service as an investment to get the client money, and make money investing that money.

At some point banks started to charge for services and nobody could live without banks anymore, so he was writing cliper86(?) scripts to discover the 'profit' of a new client.