I think the Drug War only continues because it benefits the government and prison developers.
The government generates revenue through asset forfeiture:
"...civil forfeiture is a legal fiction that enables law enforcement to take legal action against inani-mate objects for participation in alleged criminal activity, regardless of whether the property owner is guilty or innocent—or even whether the owner is charged with a crime. Civil forfeiture actions are in rem proceedings, which means literally “against a thing”—the property itself is charged with a crime." (1)
"We did not seek to determine whether forfeiture activities ultimately reduce crime or affect drug-related arrest patterns. However, we found some evidence that police agencies engage in forfeiture practices that maximize their potential for revenue generation. Specifically, we found that significantly fewer equitable-sharing payments are collected in generous forfeiture states, which is consistent with the policing-for-profit allegation put forth by forfeiture's critics (e.g., Blumenson and Nilsen, 1998)." (2)
(1) Williams, Marian R.; Holcomb, Jefferson H.; Kovandzic, Tomislav V; and Bullock, Scott, "Policing for Profit: The Abuse of Civil Asset Forfeiture," The Institute for Justice (Arlington, VA: March, 2010), pp. 9-10.
(2) Worrall, John L. and Kovandzic, Tomislav V., "Is Policing For Profit? Answers from Asset Forfeiture," Criminology and Public Policy (Columbus, OH: American Society of Criminology, 2008), Vol. 7, No. 2, p. 237.