Imagine a world where every time you drink a beer the alcohol content varies from 1% to 99% and you never know what the alcohol content will be, and have no way of monitoring your intake.
How many people would die of alcohol poisoning in that world that don't today because alcohol is legal and regulated? How many people would become alcoholics by accident because they have no control over their "dosing" when drinking?
The world described above is exactly the world that exists for opoid users when drug prohibition exists. Tens of thousands of Americans die every year and hundreds of thousands become addicts because the black market doesn't give a shit about consistent dosing. Or not cutting their product with something deadly.
This is one of the many many reasons why drug prohibition is worse than legalization. Black markets don't care about quality. They don't care about any laws like keeping their drugs away from minors. They don't care about you.
Oh and before anyone asks. I don't drink or do opioids. Never been drunk in my life (too much alcoholism in my family). I don't have a problem with other people doing it, just not my thing but I recognize the harms caused by prohibition.