Drug use can ruin your health. It ruins your brain and your liver, it invites angels to corrupt your soul, and it wastes money that, at this critical time, is vital to prepare for when the dollar has zero value. Excessive drinking can also do the same.
As there are potentially devastating consequences for doing these (smoking is included as drugs), those consequences are punishment enough for anyone that chooses to do them. That is why I never smoked, never got drunk, and never touched drugs--not because someone wanted to add more punishment to the already adequately devastating effects of drug use.