Weed is a plant that grows on it's own natually all over the world...how many athletes drink alcohol or smoke cigarettes...much more harmful and more of a "drug". Oh...but weed is illegal 
I've got to agree on this since Alchohol related accidents kill an outrageous number of people and what about smoking related deaths from Cancer to falling asleep with a cigarette, the numbers are unreal.
During 2004, 16,694 people in the U.S. died in alcohol-related motor vehicle crashes, representing
39% of all traffic-related deaths (NHTSA 2005).
Drugs other than alcohol (e.g., marijuana and cocaine) are involved in about
18% of motor vehicle driver deaths. These other drugs are generally used
in combination with alcohol (Jones et al. 2003).
You're a hell of a lot more likely to die from from a drunk driver hitting you than someone who's just smoked some weed. But alchohol is not illegal, why should weed be?