The only time the governed should be concerned with the personal decision making of a person is when that choice violates the rights of another. Your job as government, when it comes to alcohol, is to arrest individuals who commit violent crimes or cause accidents, etc. under the influence of it. The same should apply to marijuana users.
However, it's not your job to tell us that we can't do something because it's bad for us. You should only be managing the distribution of information of the damage harmful substances can cause, not forcing people to bend to the will of another's (government) perspective.
You should be spending more time on rapists, child molesters, and murderers than the personal decisions of the American people. I think that we the people would appreciate that