If you like to do business economically you can study economics, but there are many successful entrepreneurs who do not go to universities that they are rich from their own experience as well as their bravery so the need to study economics is not necessary.
Economics is really necessary to study because it brougth us the knowledge that we should able to learn in order to have a successful life in the near future .
Well you may use a table without actualy becoming a carpenter. Nevertheless, the knowledge never hurt anybody, so it is better to know how to work wood and how economically our little world turns than NOT to know it. But I would argue that devoting yourself to 3-5 years of study of economics is a little overflous and there are other ways to bring success into one's life.