Gunn '08 graduate here. It's because these intelligent, rich, and powerful adults are used to pushing themselves to the max, and they put the same pressure on their kids. However, not all children are like their parents, and a lot of them can't take the pressure.
Growing up in Palo Alto is weird, especially if you've lived somewhere else. Everyone is pigeonholed into being academically successful, creative, bright, and happy. All the parents want their children to be successful like they are. All the teachers want to create a demanding and rigorous academic environment that pushes these kids to the limit. But no one ever asks the children what they want, or gives them room to develop an identity of their own.
Instead, from the age of 7 you're expected to spend 8:00am - 3:00pm in school. After school your schedule is stuffed with extracurricular activities, ranging from sports to speech and debate to Kumon. Then you get home around 6-7pm and work on homework til midnight. Get up the next morning at 6:45am, rinse and repeat.
If you don't follow this schedule, if you opt out and don't take the required extra-curriculars or get a B in Algerba 2A/Geometry instead of an A, you're viewed as a loser. You're on the path to becoming a nobody in life. You're nothing.
So kids opt out by getting shit grades, playing video games, doing drugs, and some have serious mental issues and end up killing themselves. The adults then all get up in a panic. The teachers make long speeches about how they're here to help. The parents go to meetings and undertake inane measures such as posting guards at Caltrain, which doesn't really do anything.
Meanwhile, nothing changes. The teachers continue to assign an insane academic load, and give no room to the kids to breathe with the endless homework assignments. The parents continue pressuring their kids, because "yeah that other kid killed himself, but surely that won't happen to my child. My child will grow up to be smart happy and ambitious like me..."
... right?