From my P.O.V., the biggest benefits to legalizing marijuana are:

1.) Reduction in the overcrowding of prisons

2.) Reducing crime by keeping people off the streets

3.) Health benefits for people with specific chronic conditions, which can contribute toward reducing overall health care costs

Smokers of marijuana should ideally only partake when they are in a social setting surrounded by others whom they trust, especially when there are some "sober" non-smokers on the premises.