Weed is a natural neutral state-maker, it can seriously help and is a therapeutic. Here's why Weed is so shunned though. It's actually a law set by racist politicians to make the Mexican seem evil, here's a statement by a government official under Nixon's cabinet, and is an overall asshole.
“We knew we couldn't make it illegal to be either against the war or black, but by getting the public to associate the hippies with marijuana and blacks with heroin, and then criminalizing both heavily, we could disrupt those communities. We could arrest their leaders, raid their homes, break up their meetings, and vilify them night after night on the evening news. Did we know we were lying about the drugs? Of course we did!”