[Lean-Right]

Of course not. Take away the
criminality and more will try
abusing whatever activity they
weren’t allowed to do before.
All drug abusers started somewhere,
doing away with possession laws
will just make it easier to get
started.

[NobleFree]

The grave intrinsic harms remain. To repeat: Is the illegality of heroin or meth YOUR primary reason for not using them? It's way down on my list.

Of course not. Take away the criminality and more will try abusing whatever activity they weren’t allowed to do before.

Your first sentence contradicts your second: if you have the good sense to avoid those drugs for reasons other than legal status, then so do others, so there would be little if any increase in addiction after legalization.