From one of the world's best experimental economists, here's an excellent summary of just why economics is so useful to study as an undergrad.
Economics is a good background for all of the social sciences, business, management and law. It is also very useful in engineering. It is a central body of science with broad principles that have applications throughout most other fields. So, regardless of what the student plans as a profession, economics is a good place to start. Those who want to become professional economists should understand that it is a technical subject as is any other science or engineering.
via interview.