How do you know that? Misery loves company and since in your world of legalised validated crack, your neighbor could be holding crack parties all day.
But of course you would still be happy as a clam.
So? That would do me no more harm than a drunk living next door. If he did find a way to do me harm, I would deal with that problem directly, rather than agitate for Prohibition. Outlawing all drugs or booze or whatever is a very inefficient way to solve a problem being caused by my neighbor.