Is it permissible to kill drug and alcohol distributors who commit fornication, especially if the police are complicit with them and take no action against them?

You have done well in your zeal for the sacred limits set by Allah, and this is from the core of faith. Drinking intoxicants and using drugs, as well as promoting them, are great abominations that lead to widespread corruption, and a Muslim must denounce them. Changing evil with the hand is exclusive to the authorities and not for the general public, to avoid chaos. Therefore, it is not permissible for you to harm drug dealers with killing or anything else. If you are able to denounce them with your tongue, then do so; otherwise, by denouncing it with your heart, you absolves yourself.