I very much disliked my middle and high school years (despite doing fairly well academically). I felt like I had little control over my life, which really irritated me. College, on the other hand, was a completely different ball game… loved it immensely. It was a 180-degree experience for me, and I ultimately ended up with a Masters in Engineering.
Moral of the story here: don’t judge a child’s outcome in life based on his/her views of high school. High school life is tough on some kids, especially those who are more independent and tend to be free-thinkers. These kids will often thrive in a college setting where they have more flexibility over their lives.