Answer:
From personal experience by a friend/family member:
They mostly cause danger and trauma, whether you're a person "buying" them and you scam them, they won't hesitate to hurt you or worse, if you don't pay the full amount they acquire. If you're the person doing them, can cause trauma by doing them in public areas, or if you're a parent and your kid(s) manage to see or get ahold of the substances. Little kids seeing the dangers and the effects of substance abuse, they'll be constantly reminded of that moment everytime the word "substances" gets brought up, on the news or in real life conversations.They also cause trauma by robbing and you're the main influence being held hostage, etc.