also, not an expert by any stretch of imagination, from what I understand though some drugs, like meth for example can get just about anyone addicted to them after one-two uses.
As for preventing use, good luck!
As for "legal drugs" vs. street - you're not seriously comparing the Desoxyn dosage some kid with add would get prescribed to him with a dosage a user would smoke are you?
Not only is this the dominant view in the various recovery communities, it's supported by considerable scientific evidence - for example, addiction is well known to be inheritable, and childhood trauma is very strongly established as being predictive of addiction in later life.
I take it you don't know many addicts, especially former addicts with a mature perspective on their own addiction. There are some really good books written by folks who've been addicted and gotten over it that could clue you in on how addiction works.
> you're not seriously comparing the Desoxyn dosage
Most meth addicts start with a dose that helps them, emotionally or as a performance enhancer for work, school, sex, etc. These doses are roughly the same as those prescribed for ADHD and narcolepsy. Eventually, meth stops helping and takes control - this is the hallmark of addiction.