In this day and age, when one can simply go on the Internet and print out a high school diploma or take a trip to Mexico to become a doctor, you might find yourself wondering what's the point of wasting away 12 or more years of your life in what is essentially tax-funded day care for teenagers.
School is supposed to prepare you to be a successful adult, having a job, a house, $8,000 in credit card debt and so forth. So maybe you hate having to get up before noon and staying up until 4 in the morning writing a paper on the science fair project you didn't do earlier, but look at it this way: Most adults hate their jobs, too.
No one can honestly say that everything you learn in school is important. Some of it is about as useful as a degree in philosophy.
However, there are some things that are essential to being a successful adult, or at least not bankrupt. So the entire purpose of a school is to prepare you for real life.