Nobody starts of planning to get addicted. And while they certainly should realize that's a risk I'm not sure it ever factors into anything. Much like harsh punishments don't actually deter crime.
Sometimes we take decisions without being fully aware of the consequences (or simple choosing to ignore the consequences), but this doesn't make us less responsible. Nobody drives intoxicated planning to have an accident, for example.
And of course punishments deter crime. Not the crime that happens, obviously, but the crime which is never committed. There would be more rape, theft and murder if there were no consequences at all.
the same way all the high speed accidents happen to people that started driving at the «harmless» speed of 20km/h.
What I want to say is that demonizing marijuana can allow a bad comparison in the form "marijuana did nothing bad to me, all the thing they say about drugs are nonsense, so I can move to other drugs and be ok".
Truth is marijuana is harmless, compared to almost all the other drugs, including alcohol and tobacco.
