Marijuana's illegality in America seems almost arbitrary when compared to other (and legal) things that are readily available.

Though alcohol can ruin people's lives (and in many cases kill), it is completely legal to purchase and have as long as you are of legal age. It's the same thing for cigarettes, they're addictive and cause cancer, yet you can still buy them at the gas station like they're Skittles if you're old enough. (Even with the age restriction, if people want it, they will get it.)

Regulating things around the basis that they can (and will) be abused is logical, and for that reason there are laws against driving while intoxicated because irresponsible people can endanger others. There's only prosecution when harm can possibly be done, not when you just own the thing that makes it possible.

I don't think it should be any different for marijuana.

On top of this, It has medical uses ranging from Parkinson's treatment or stress relief, something that can't be said for alcohol or tobacco. In this case, I feel like the pros simply outweigh the cons in almost every aspect.