There are lots of reasons, not least that a strong Econ student can take a lot more math than a business student and that is sought after in IB and consulting. The top Econ students may well be stronger academically than the top business students, but most important is that you are in the top few percent in whatever you choose to do. If you apply for one of these jobs from IU you’d be competing with some of the top students at Berkeley anyway, so I don’t see why you would avoid trying to compete with them in college.