Thus you must support another try at alcohol prohibition. Nothing less would be logically consistent. Alcohol intoxication makes you very dangerous to others if you are so foolish as to drive but probably does no harm if you do so in the confines of your home. Long run health effects make alcohol much more dangerous on many counts. Short run health effects again make alcohol much more dangerous. You can actually consume a lethal dose of alcohol (or Heroine, cocainc, etc) at one sitting. That is not possible with MJ. No lethal dose has been identified since no one, in all history, has ever died of an overdose of marijuana.
Most substances are dangerous in some large dose and useful in lesser doses. It is just NOT the business of government to make mere possession or responsible use of some, politically selected, substances a crime since no one is hurt.