Parents need to stop trusting their kids and start watching them.
The problem is that they don’t pay enough attention to their kids.
Watch them you can tell if they start using drugs.
Leave a couple of bucks lying around , see if it disappears.
Be leery of their stories of where they are going, check up on them once in a while. A kid that knows they are being watched will think twice before they start using.
I once told my son that if he started using he and I would be making a personal visit to whoever sold him the drugs.
We wouldn’t be going for a party.