My students are in the middle of making decision on what they want to study for their bachelor degree. Although I cant prove mathematically, but I strongly believe most of them are deciding based on post graduation career prospective. Other than that, some decisions may be made under heavy influence of parents' expectation.
I feel sorry for those kids, who somewhat feel the burden of being future graduand. Whatever their decision will be, there are two things I hope they wont forget; first, be happy and second, be a good person who benefits others.