Honestly answer this simple question:
To what extent has the legal status of any substance influenced your choice to either take or not take it?
A recent study by the UK government across a number of countries has confirmed that there is zero correlation between the severity of drug laws and the use of drugs in those countries.
http://www.bbc.com/news/uk-29824764
Two interesting examples stand out. Since Sweden toughened its drug laws, the consumption of drugs in that country has increased. Portugal on the other hand, decriminalized the possession of all drugs (even heroin) and now has a lower consumption of drugs amongst its population than before.
I think any rational attempt to understand the problems associated with drugs, (assuming the intent is to minimise the damage they do to society) must make a clear distinction between the harm that the drugs actually do and the harm that is done by attempting to police the issue. ie) the billions spent on law enforcement and the creation, enrichment & empowerment of criminals.
The war on drugs has not resulted in any tangible benefit to society but has come at an extraordinary cost.
By any metric I can think of it is an abject failure, so why not consider the words of Albert Einstein:
Insanity: doing the same thing over and over again and expecting different results.