I don't smoke weed, just because it generally doesn't do much for me but make me "dopey". I have lots of friends who find it quite beneficial, and all the power to them. It makes no sense to me to set billions in law enforcement efforts against something which by any objective standard causes almost no harm. And then to hand over billions to international drug cartels is just disastrous for governments and people.
I appreciate the point raised earlier that the US Constitution requires special amendment to legally infringe on citizen's rights, but it's been done anyways, and so many people jailed, killed, and lives ruined. Here in Canada our constitutional rights are far less, and less respected. Now governments eyes are all a glitter over the revenue prospect, so they still need a legal framework to impede the growing of something akin to sunflowers. I still see that as a ridiculous situation, as any farmer could probably supply their whole state for a year from one field. I think it would be best if the product had no significant value.
The only concerns I have are the obvious risks of smoking, and there's a significant increase in schizophrenia amongst young smokers.