It's an arms race. When most top kids took 1-2 AP classes, those who really wanted to stand out would take 3-4. When most top kids take 10 AP classes these days, those who really wanted to stand out will need to take 15. When most top kids take 15 APs, those who want to stand out will take 20, invent something, play multiple instruments, win some national competitions, be the captain of the varsity team, build schools in Africa...

And no matter how much kids (and parents) stretch themselves, the top universities accept a fixed number of students.

The real question is how big a difference in career, earning and life one can make by having the name of a prestigious college on one's resume.