[d0liver]

My GPA was bottom 10ish at my high school. I graduated high school essentially because I already had most of the credits I needed to graduate from middle school. I got into college based on test scores alone (and I was surprised that this was possible). My GPA improved a bit early on in college and then improved much more around junior year once I started getting into harder classes. I ended up graduating with a math + CS double major in 4.5 years.

So, sometimes people are just bored. And there are a bunch of other factors here too - perhaps the biggest one being that "graduated within six years" is not a great indicator of success. Linus Torvalds did not graduate within six years but did build the first version of Linux at university.

GPA is a good indicator of how much work you're willing to put into what you're learning _now_, so it tracks well as a predictor of how much you care about GPA which is a pretty good predictor of whether you'll graduate in X years and probably not much else.