In all honesty, a friend and I were just discussing last night the "opportunities" we've had to make the same mistake that one of these families made years ago. For various reasons, we didn't get caught in the grip of drugs, but one seemingly innocuous decision at a party could have changed the path of our lives forever. And we'd both had multiple chances to make the same bad decisions. We didn't always make the smart one, but, luckily, we somehow got away unscathed.
Its not like someone wakes up one morning and says, "Today is the day I do something that will cause my life to spiral out of control." People make choices, based on their lives up to that point, that they honestly feel are good or safe or trivial. With hindsight, they might realize otherwise, but unfortunately that is sometimes too late.
One simple decision, often to go along with the crowd at that moment because you so desperately need to be accepted or liked, can have major repercussions. Once you step through the door, so to speak, you will experience things that may cause you to make ever-worse decisions. Unfortunately, many around you are not going to stop you, they are in the same trap. Misery loves company.