Frustrations

Why do people who are capable of so much more not do anything? I recently heard of someone who doesn't do their homework or try on their work so they make bad grades but got a 27 on the ACT. Why do people do this? It makes me soooo mad, I try hard to get my grades and think through everything thoroughly so I get good grades and I studied for the ACT and just made a 24 everything I do is mediocre. I hate it, I know I'm horrible but these people do not deserve to be smart. I mean a 27? really?? thats a great score and the person was like "people think I'm stupid because I get bad grades but I'm really smart I just don't do anything" that made me so mad because being that smart and flunking IS stupid. I hope these people fail, yes that's horrible but that's how mad it makes me, they don't deserve to succeed if they're not going to work when people who do work hard could still fail because they just aren't as naturally intelligent. I know it's a stupid teenage cliche to say "Life's not fair" but it's not and it's so frustrating, I am mediocre in my intelligence, I'm not stupid but I'm not overly smart either. I guess mostly I'm jealous that I'm not that smart, it is my dream to get a 27, I've taken it twice and made a 24 both times. I want to go to medical school and be a doctor, that won't ever happen with a 24.