Right, I don't see it getting legalized in the United States any time in the next few decades. The only reason it's illegal worldwide is because Harry Anslinger used America's influence in the United Nations to coerce over a hundred countries to consolidate their drug policies into one pretty much dictated by America. America has been at the front of the war on drugs, going so far as to violate other nations' sovereignties (meanwhile the CIA continues to play an active role in the international drug trade...). The govenment has more than enough information at its disposal to determine that cannabis is far less harmful than either alcohol or tobacco, and politicians either ignore it for the sake of not tearing apart their pre-existing beliefs or because most people wouldn't stand for it and they'd lose votes.

The system doesn't allow serious challenges to long-standing policies like cannabis prohibition. The goverment isn't going to do anything because the people don't seem to want it; the propaganda campaigns have been overall quite successful in swaying the gullible masses. And the people aren't going to do anything because the government has imposed such strict policies and stigmas on the activity that practically no one is courageous enough to publicly admit to having tried pot, much less advocate its legalization.