The #1 reason listed by the University of Southern California: it pays.
Now, I won’t go so far as to call this fact trivial. Rhetorically, given that we value everything in terms of money (so that value just means monetary value), this may be a good strategy. But, really, what this graph shows is that we should all be majoring in computer science — assuming that money is the highest value.
But this data may well be of use to the academic philosophers in Florida, who are facing the prospect of differential costs for majors (charging more for humanities and less for STEM majors, on the grounds that STEM majors will make more money).