There's plenty to support this claim: consumption prevalence and disorder prevalence.

Opiod users are vastly over-represented in all sort of statistics - addiction treatments, overdose deaths etc as compared with alcohol.

6% of alcohol drinkers are diagnosed with alcohol use disorder, the number exceeds 50% for meth users.

https://www.cdc.gov/mmwr/volumes/69/wr/mm6912a1.htm

> 6% of alcohol drinkers are diagnosed with alcohol use disorder, the number exceeds 50% for meth users.

This seems like numbers you can not compare fairly. I would think if alcohol were illegal, a bigger percentage of users would be diagnosed with alcohol use disorder.

Diagnostic criteria are quite agnostic (badum-tss) towards the chemical in question.

You could also argue that people consuming illegal substances are less likely to report for treatment and be diagnosed in the first place.

Why is it so hard to accept that different substances are differently addictive and harmful, per capita? Would you shoehorn chocolate and coffee to the same bucket?

I am just careful in this area because previous policies have not been based on scientific evidence, but political agenda (as expanded upon other-where in this thread). So I don't trust my common sense... I accept that different substances have different effects.

Harm is a domain that is very broad and hard to quantify fairly I think. Does Meth cause more harm because more Meth addicts have fallen out of society than say Coke? If so, how can we make sure to differentiate between mere correlations and causal relations?