There is this substance called spice in the U.S. And it is sold as incense. But it has the same chemicals as marijuana. Customers use it in order to get high of it. I see a lot of the Muslim brothers selling it in the stores. When I tell them this is haram, they reply "No, we sell it as incense and it is up to the people to use it however they like". My Question is, is it haram to sell these kinds of things.
We believe that when a thing is sold for good purposes and it is misused by some then the sin is upon the users. For example if one sells grapes which can potentially be used as fruit and juice. It can also be used to make wine and strong drinks. This does not mean that sale should be prohibited and declared haram. Therefore, I believe the reply you get from these people is sound as long as the thing is no more used as edible and is used for the evil purposes on a large scale. In such circumstances the government should act and the people offering it in their stores too should grow conscious.