I don't agree with the development part, but I agree with the waiting til 18 part (altho i started smoking when i was only 16, almost 17). My reason is that MOST people start doing drugs, or smoking, or drinking or whatever as a result of their peers and NOT because they made a conscious, informed decision to do it. I believe that at the age of 17 or 18 most people are sensible enough to decide the risks/benefits for themselves, and act accordingly. I know this doesn't apply to everyone, some ppl mature early and others late, but in general i think my point is pretty valid.

The brain development shit is bullshit IMO tho. Your brain doesn't fully develop until you are 25 correct, but after that it deteriorates. Mention that next time someone tells you the "wait until you're 18..." shit. Say, "well if you think weed wrecks your brain, you think it's a good idea to enhance it's deterioration?!"