A new survey in the Lancet comes to a sane conclusion about the relative dangers of various drugs:

Heroin and cocaine were ranked most dangerous, followed by barbiturates and street methadone. Alcohol was the fifth-most harmful drug and tobacco the ninth most harmful. Cannabis came in 11th, and near the bottom of the list was ecstasy.

That's why we criminalize pot and ecstasy, and allow massive distribution of booze and tobacco. Marijuana is a gateway drug, after all. If you smoke it you might move on to far more dangerous substances, like beer.