Drug legalization it one of the big differences between the libertarian and the conservative. Being a conservative I don't favor legalization. I think that we have enough recreational drugs. There is no good that will come out of legalizing drugs.
Many people say Marijuana is a wonder drug. It will save trees, it is better than cotton for clothing, and it has a lot of medical purposes. People will site all these reasons and others as to why it should be legal. They act like they want a better world for all. But when you ask them if they want it legal so they can smoke they will say "yes". Then ask them "why do they say all these other things rather than 'I want it legal so I can smoke it.'" They will give you a wide range of reasons why they don't. The simple fact is that they realize that most of America is not for legalizing another drug for recreational purposes.
As to the arguments of saving trees. They say that hemp makes great paper and could replace trees. That would save all our trees. But they forget that trees are used for fuel, and wood to build houses and other buildings.
THC is the active ingredient in Marijuana. There are some hemp plants that have zero to near zero THC. Ask them why don't we grow these plants to make paper and clothes. Once again they don't care about paper or clothes, they just want to get high.
Medical purposes for Marijuana (THC) include helping to ease the sickness cancer patients have after radiation treatment. There is a man-made form of THC they can use. So once again this ruins their argument for making Marijuana legal.

Drugs are not good for you. People do not need drugs to have fun, relax, or enjoy themselves. If they seriously do then there really is something wrong.