IT!!! doesn't do anything - but grow. It just sits there and grows period. If someone wants to do something WITH IT then that's a different issue.
So just let it sit there and grow. It will be quite happy. Or smoke it and you will either be quite happy yourself of kinda bored depending on how it affects you.
Whether it or any other substance should be legal or not or whether you should be allowed to ingest something or not is an issue of personal freedom.
If someone you love is taking a substance that is bad for them, I don't see how that should become a legal issue.
If you really insist on restricting personal freedom and want to start banning things. Then perhaps we should look at religion. How many people are have been killed this year by 'religion' (speak up Shrub, here's your chance) and how many have been killed by pot?