The studies did not make sense. They didn't compare with the IQ of abuser of other drugs, like alcohol, game, TV, etc.<quoted text>I agree, studies have shown that pot makes kids lower IQ's.
The samples were quite small, and their conclusions were biased.
On most comparison points, individual and social, cannabis appears to be far safer than alcohol, so its legality can provide a choice which can reduce the harms.
Then in case of abuse, undesired habituation or addiction, some drugs, like Salvia divinorum or Tabernanthe iboga, can cure that condition. Criminalization of abuse of a product only aggravates the problem. Addiction can be cured, with non addictive drugs.