your understatement of the human body is incomplete because most of the drugs do have a endogenous version
Heroin=Endorphine
THC(Cannabinoids)=Anandamide
and your claimed negative effect is bullshit because the most of the drugs do not have any negative effect.
Anadamid for example or Tryptophane to get Serotonin
and your "Junkie" claim is also invalid because there are highly effective medicine to cure addiction for example Iboga against Opioid addiction.
also your "dopamine" claim is bullshit because million of people use L-dopa (its the same dopamine) as a medicine against Parkinson diseases
[...]
so you use cannabis and maybe alcohol and i use GBL

its much healthier.