Yea, well, that would matter, if the cost of being addicted were actually significant, in a legalized regime, such as occured in the US between the Civil War and World War I.
The best we can do is look for a comfortable middle ground. By comfortable, I mean a balance of:
education of the hazards of drugs for our youth
lowest cost and danger to our citizens as a whole
respect of individual freedom and personal responsibility
We are not going to completely eliminate drug abuse.
Seems to me the magic formula for this problem as with most other social problems is to make the problem more of a pain to the addict than it is to society. (a take on the personal responsibility angle)