The prohibition on drugs is an attempt to limit the amount of devastation which We The People are then on the hook for fixing. I don't deny that the War on Drugs has failed. There is a lot of devastation, and the prohibition has not really limited it.
But we should stop paying for the cleanup. People who make bad choices should suffer all the consequences. If we got rid of the Nanny State, people would find that the bad aspects of drugs would quickly outweigh the "fun" aspects of drugs.
Step 1) Eliminate the Nanny State
Step 2) Legalize drugs
Doing it in reverse order would be really, really stupid (you'd never get people to agree to removing the safety net after so many additional people were using drugs.
Yes!
People killing, robbing other people to support drug habit=crime
People killing, ruining themselves using drugs=natural selection.