Anyone who has used marijuana can say that it is far less dangerous than alcohol. As my lawyer always says "When you drink you want to get into a fight, when you smoke marijuana you just wanna watch movies and eat pizza. Who can get hurt doing that?"
In 2009:
36,547 died of suicide
36,284 died of motor vehicle accidents
31,224 died by firearms
30,504 died from accidental poisoning
23,199 died due to alcohol induced side effects
0 died from marijuana use
Source: Kochanek KD, Su JQ, Murphy SL, et al. "Deaths: Preliminary data for 2009." National vital statistics reports; vol 59 no 4. Hyattsville, MD: National Center for Health Statistics. 2011. pp. 17-20
You can get it on every street corner. Prohibition hasn't stopped anyone. We might as well tax it and make some money off of it.