I've got doubts about the safety or health benefits about marijuana. I don't smoke it, mostly because it is illegal, but partly because I remember when i tried it it was very harsh on my already delicate lungs. Legalizing it wouldn't change those doubts for me. And it being illegal hasn't stopped the vast plurality of acquaintances of mine from smoking it. Just me because I'm hyper chicken about such things. That risk from inhaling smoke seems to me to be the same risk as from smoking cigarettes. So if it ever does get legalized I doubt I'll smoke it anyway. But all that is beside the point. It almost got legalized in the early 80's, but a PR campaign, and some evidence from Egypt, convinced people it should remain illegal. Since then the evidence shows that it's not harmless. But if one made a scale look of it's harm relative to other drugs and products the chart might look like this.
The right way to regulate cigarettes is by keeping them legal but restricting access. The same has been found for alcohol. Prohibition sends use underground and actually enhances popularity. Restricting sales to drug stores, liquor stores and similar outlets keeps them where law enforcement can watch them, and lets the government recover some of the health costs of their use. It seems to me that marijuana should be legal, sold in a restricted manner requiring ID, and use in public, while driving, or at work restricted. This works (more or less) for alcohol and cigarettes. I suspect it would work for Marijuana.
And it is insane to prohibit growing hemp.
People should have the right to do their private business without fear, and I suspect that includes the right to drink or get high. That changes when people's rights infringe on others as in common spaces like work, which is a privately governed commons.