Why is Marijuana still an illegal drug ?!

I really don't get how governments are still prohibiting Marijuana, and labeling it as illegal. 

I mean, we have already come a long way with the legalization process so that it's now legal in SOME Countries at least, but still, this is ridiculous. 

Marijuana doesnt kill people. 

Alcohol and cigarettes, which are perfectly legal and socially acceptable, do. 

Marijuana doesn't make people aggressive.

alcohol does. 

Instead, Marijuana makes people happy and leaves them inspired.

Marijuana doesn't hurt the body, or its organs, or inhibits its functions. 

Alcohol and cigarettes both do that - immensely. 

Instead, Marijuana even HEALS the body, and can help treat cancer cells !!!

if the government would finally legalize it, it could even make billions of $ each year due to the taxes, that are now being lost on the black market. 

So tell me, WHY would there still be a reason to consider marijuana an illegal drug. It just doesn't make any sense! It's more a medicine than it is a threat!