It's unclear that the numbers are in your favor. As far as I can tell, as of 2018, the US had 600 opiate users per 100k, Portugal had 250, and Singapore had 30.
So Portugal has twice as less addict than the US, even though drug users don't risk anything legally, while in the US using drugs once can mean decades in jail.
"Singapore has the world's highest percentage of millionaires, with one out of every six households having at least one million US dollars in disposable wealth."
https://en.wikipedia.org/wiki/Singapore
Singapore is a 5 million people country.
Prohibition isn't the important factor here.
Dealers get shot on sight in Brazil or in The Philippines, that's not just prohibition, that's state-sponsored murder, at scale and that doesn't stop anyone.
It's not unclear if you're not looking at an extremely small subset of extremely rich and privileged people.
"Always" as in 1972 - after nearly a century of suffering the aftereffects of the opium wars. The Singapore Economic Development board predates the harshest drug laws by a decade and when the law came into effect, Singapore was already well into its economic miracle.
Singapore has only been independent since 1959. The date you gave is when the Misuse of Drugs Act was introduced. They still had harsh punishments prior to that through the legal system. Like I said earlier in the thread, whether the benefits are worth the costs is a political question, but prohibition appears to work in Singapore. By the way, since you brought up the Opium Wars, Mao also basically eliminated the production and use of opium by using harsh repressive measures as well. It's why most poppy production now takes place in the Golden Triangle. Just prior to 2001 the Taliban also basically eliminated poppy production in Afghanistan, but the US invasion led to the reversal of that.
Yet, Singapore had a death rate due to opioid overdoses of 0.16 per 100'000 inhabitants and Portugal 0.25 per 100'000. I'm sure if you'd include the draconian punishments in Singapore, then there is a clear winner in which country does the least harm to its citizens.
https://www.apa.org/monitor/2018/10/portugal-opioid https://www.washingtonpost.com/opinions/singapore-is-winning...