reason 1: To smoke lots of pot, waste your parents money and get kicked out.
reason 2: To get a piece of paper stating that your brain is full of shit information that you probrably already learned from the "magic schoolbus" and that you are allowed to work somewere other than a fast food restaurant.
Mom: That's great son.
Dad: How much will it cost?
Kid: Around 10k.
Mom and Dad have heart attacks and die later in the hospital. Kid goes to college, but than drops out cause he's stupid.