"They tell us not to do this, It must be pretty fun!" - Exact Mindset of all but the stupidest.
Schools try to associate drugs with the worst of the worst. Coke, Meth, and Heroin seem like just the stupidest thing ever IMO, but things like Pot, LSD, Magic Mushrooms (Removed from most curriculum), and the like aren't as bad. Quote directly from my Health Teacher,"Drugs similar to LSD will accumulate in the fat in your brain, and leave you in a permanently disabled state." Like hell they do. These are the same people who praise Lance Armstrong. "Oh Lordy, He survived cancer, he's the most badass guy ever!" Oh hell no. He did survive cancer, but for what? People could praise him for all the Performance Enhancement Drugs that he took, all the EPO and extra blood that was pumped into him, and all his team member who cheated along with near every other Pro Cyclist that has a good enough doctor to falsify tests for EPO? I wouldn't have a problem with him and all his drug buddies if they wouldn't have won millions of dollars that rightfully belong to those who don't cheat?
Tl;Dr, People are asshats.