You can die from too much marajuana, its called carbon monoxide asphixiation (choke on smoke happens a lot in structure fires)
Marajuana is fine in moderation, hell its safer than cigarettes (in long term health)
But If marajuana was leagalized guess what, the govenrment would sick its caock in to the profiets by taxing the shit out of it, so eventually it would probably be the same price as if it was illegal. So you the consumer would still pay assloads for it.
then it would cause the lack of modivation decreasing in productivity in the economy resulting in masses of irresponsible low income slackers
no one wins if its legalized.