Because if I accidentally break the speed of sound over a town I can inadvertently blow out every window within a 3 mile radius. Then get grounded forever and have to explain why I was a dumbass.
This is prevented by some smart engineers studying the location of Mach 1.0 relative to calibrated airspeed in different conditions and making a computer system which translates all those variable into a simple, easy to read display on the bottom left of my HUD telling me to slow the fuck down.
So that's one example I use every day, but for you it's to challenge yourself and learn more about the world. Also, if you do well you can separate yourself from your peers and get into more challenging schools later. Or maybe it's just another problem to foster more advanced thought and develop cerebral growth. All good answers, pick the one that's best for you.