A simple utilitarian argument against drug dealing is that while the user may experience a great deal of pleasure, their family and friends are hurt more. But does this argument hold once a critical mass of people are hooked?
Imagine you are a heroin dealer. And imagine the region you work in is a connected graph, with each node being a person. Distance between nodes represents how close the relationship is and thus how much it will hurt one if the other is an addict. You start dealing to one person. He is totally satisfied in his drug-induced stupor, but his contacts aren't. So one person is ecstatic, 8 are despondent, for a happy-to-sad ratio (HSR) of 1-8. This could be represented by the following graph, were X's are sad people, and O's are addicts.
X X X X O X X X X
Now you expand your operation to those 8 people as well, meaning now there's 9 ecstatic people to 16 despondent people, for an HSR of 9-16.
X X X X X X O O O X X O O O X X O O O X X X X X X
Again, you expand your operation in the same way. The HSR here is 25-24.
X X X X X X X X O O O O O X X O O O O O X X O O O O O X X O O O O O X X O O O O O X X X X X X X X
Expand again and it's 36-28.
X X X X X X X X X O O O O O O X X O O O O O O X X O O O O O O X X O O O O O O X X O O O O O O X X O O O O O O X X X X X X X X X
There seems to be an inverse-square law situation going on, where the satisfied grow exponentially and the hurt grow linearly. Even if you loosen the standards such that being mildly inconvenienced counts as being hurt, all that does is mean drug dealing requires more expansion before its benefits outweigh its costs. The same is true if you have a higher number of relationships-per-person, the more addicts there are, the more relationships will be addict-addict rather than addict-sober.