If Experience Is A Good Teacher, Why Do You Keep Repeating the Course?

We all know the saying, "Experience is the best teacher." But how come many of us repeat the course?  Why do more among us don't necessarily learn anything under the instruction of even severe experiences?  Well, experience, like every other teacher in school, can teach only those who are willing to learn. The secret is to learn enough what mistakes need to be avoided and what principles need to be applied to the issues of life. If we don't, we fail to pass the course and need to face the same teacher again!