When you’re young you need to appreciate the long-run repercussions of your actions.Your freshman-year grades impact your choice of colleges, which impacts your career trajectory and social network, and so forth. You need to apply intelligence.
Smarts matter less than we would like. What often matters just as much, if not more, are soft skills. Things like building and maintaining relationships, or the way that you present yourself to others. Soft skills actually are more important than how smart you are. You must be socially fluent and naturally able to build rapport.
Finally, it’s not about what you know, but rather what you can do. If you cannot apply your knowledge, employers do not care about it. An employer really wants to know: what skills do you have that apply directly to the narrow functions assigned to the job for which you’re applying?