Abusing drugs can bring out the worst in people, but as long as they're only hurting themselves, it shouldn't be anyone's problem but theirs. However, when they happen to have children, that's a whole different story.
Being a drug addict and raising children just don't mix, considering how in order to be a responsible parent and good role model, you should be in your absolute best behavior, and not to mention extremely attentive and patient.
Formal drug dealers on an r/AskReddit post shared a couple of remarkable stories of how they were so shocked by their customers' lives, that they felt like they had no other choice but to call child protective services. By doing that, they ended up saving those kids' future and lives.