The decades long war on drugs is proven to not be successful. Not only are drug offenses not related equally and harbor a racial bias based on their prosecution levels, but all the war on drugs has done is put people in prison and help to continue drug wars in the South.
With the amount of money we spend on the war on drugs every year, which is currently approaching $40 billion so far spent by federal and state agencies this year, we could more than fund treatment, prevention, and outreach programs. On top of abolishing a failed war that's costing taxpayers money, you would have the added benifit of a likely tax of an substance that could be sold. Another benefit of ending the war on drugs is controlling purity of substances so people don't end overdosing a fake drugs, and slowing the growth of gangs and terrorist organizations around the world. At the very least, on the subject of favoring treatment, simple possession of any substance should not be a crime. Those caught in the cycle of addiction could use help, not jail time.