Most drugs do not make users violent, heroin does not make someone violent if anything it makes them completely useless and doped out lol. The lack of the heroin is what makes them commit violent crimes. Now PCP/meth or some other crazy research chemicals like bath salts or something can make a user react violently, in very rare cases. But honestly I think all synthetic drugs are a form of evil and by synthetic I mean drugs that are synthetic even the ones given by doctors that don't even alter ones consciousness. My personal opinion is that drugs should remain in a natural plant form and not chemically altered to become something completely different.
But with that said doctors give legal heroin to patients (oxycontn percoset vikodin fetanyl etc.) all the time as a matter of fact in america that is how a lot of older people that were never drug addicts become drug addicts they hurt themselves accidentally get prescribed a chemical opiate by a doctor that is stronger or just as strong as heroin become addicted to it and spend all their money on the medication from the doctor and eventually start using heroin as well when they have no money a once completely non violent person now turns to crime because they have no money. So like I said MOST of the time the drug is not what causes a violent or criminal act it is the lack of funds to acquire the drug.
I agree completely with your opinion of the ridiculous drug war, and that Duterte killing drug addicts and users is abominable.
But I do have to call you out on your opinion that natural = good, and synthetic = evil. As someone who studies chemistry, this is simply not the case. Some synthetic drugs are virtually harmless, some natural drugs are dangerous as hell. And of course there are semi-synthetic drugs, which are derived from natural sources. Morphine is totally natural, and is very addictive and can kill with an overdose (Diacetylmorphine, or Heroin, is derived from morphine, so is a semi synthetic drug).
You fancy some Botulinum toxin? It's totally natural. Except it is the most potent poison known to man (and most of the most potent poisons are natural). 1 nanogram/kg bodyweight can kill a human. For me that would be about 80 nanograms.
Paracetamol is synthetic, yet a normal dose is 1 gram. Recommended dosage for 24 hours is 4 grams. single doses of 200mg/kg could kill a human. For me that would be about 16 grams.
You would need to take 5
billion times more Paracetamol to die, than Botulinum toxin, if my maths is correct.
Another lovely natural drug is scopolamine, produced in plants such as Jimson Weed (also known as Datura). A physically dangerous deleriant drug, that can cause nightmarish visions and death.