Legalize marijuana with age restriction

From personal observation, weed (marijuana) has two basic side effects: euphoria and impaired judgment. Now the last one sounds like a side effect for alcohol. So, why not make weed like alcohol? The idea is, put an age restriction on buying weed, like 21 years or older. Mix that in with a few more government rules and regulations and there is a very nice profit to be made from this, and allowing more jobs to be made. Since there are different types of weed there needs to be a classification system, i.e. Class A physical highs, Class B mental highs, Class C combination, etc...Also, a new set of regulations would need to be made to keep everyone safe, i.e. don't smoke and drive or face jail time. Since just legalizing weed makes people unhappy, this should satisfy the majority of both sides