Is being born with natural intelligence the only way to succeed in college?

It really depends what your career plans are. For example if you plan on going to grad school specifically med school you need a 3.7 gpa at minimum for any chance of admission to an MD school. When colleges have on campus job fairs many times companies will have a minimum gpa to be considered for a position or even an internship. I remember some consulting companies requiring at least a 3.5 gpa.