<p>The problem is that access to the next career level, whether it is admission to grad/professional schools (med/law) or job, as well as scholarships, bonuses, etc. are all primarily number driven. While there’s some adjustment for the selectivity of the school, there isn’t really for the difficulty of the difficulty of the major, the program, or grade deflation at schools like Berkeley. So, if you spend 200K and work your butt off, why not have it a little easier and major in another field rather than be in the lower half of a group of smart people? Of course, the more drop out, the more challenging it becomes for the ones that stick with it.</p>
<p>Also, while there is a lot of talk about the need for more STEM majors, the career outlook in the sciences is actually pretty poor, with many grads competing for few jobs, grants, and after multiple postdoc jobs, a permanent position.</p>