I don't want to make you guys think of the stereotype of teens being invincible or anything but...I'm not sure that's 100% accurate. I mean...me and my friends get good grades (quite a few have 3.5+, and a couple have 4.00s) and aside from us acting a little "burnt" a couple days after we smoke, we seem to be fine.
I'm just saying it doesn't happen to everyone.