This is an example of equivocation: Insofar as there is a definition of "drug" for which "Thankfully, dealing drugs is forbidden" is (well, minus the subjective judgement "thankfully") categorically true, it is not one for which either "Addiction needs a drug" or "Drug needs dealers" is also categorically true.
> Thankfully, dealing drugs is forbidden.
This is an example of equivocation: Insofar as there is a definition of "drug" for which "Thankfully, dealing drugs is forbidden" is (well, minus the subjective judgement "thankfully") categorically true, it is not one for which either "Addiction needs a drug" or "Drug needs dealers" is also categorically true.