Not true, nobody in the history of the world has overdosed and died from weed, for example, and it has successfully transitioned many cranky people into being non-cranky people.
Also I think it can be dangerous to not take drugs, or at least alcohol, as there's a chance you could end up bored, miserable and angry, and end up going on a murderous rampage. Hitler was a teetotaller, Osama Bin Laden was a teetotaller, there is a common denominator among such people - if only they got on the piss with mates and had a bit of a laugh more often they might have turned out differently.