"There was about 300 million pain prescriptions written in 2015,"
https://www.cnbc.com/2016/04/27/americans-consume-almost-all...
While 2017 numbers are not in. 2016 Prescription pain medications are down 6% from 2015 and down 18% from 2012. https://www.cdc.gov/drugoverdose/maps/rxrate-maps.html
And again, we are talking less than one prescription per year per person on average. With many of these prescriptions for 2-3 days worth of pain management. Though again, a minority of people get a lot of pain medication.
That article is borderline irresponsible with how it reports that metric.
80% of global prescription opiate medications are filled in the US, but that doesn't mean that 80% of those prescriptions are consumed in the US (or consumed at all). Nor does it include no-prescription opiates, which are generally much easier to obtain in most countries around the world (and also a lot cheaper) than their prescription counterparts.