Those people are not "doing drugs", they are following (bad) medical advice.
People with long term pain need better access to pain management clinics; better access to physio therapy and exercise therapy; better access to different meds; and if they're still in pain better prescribing of opiates carefully following protocols.
https://www.fpm.ac.uk/faculty-of-pain-medicine/opioids-aware
https://www.rcpsych.ac.uk/pdf/FPM-Opioids-Aware-Press-Releas...
> There has been a sharp and sustained increase in the prescription of opioid painkillers in recent years. The latest figures from 2014 show that 22.75 million prescriptions were written in England with a total cost of nearly £305 million to the NHS. Similar rises in prescribing in the US and elsewhere have been accompanied by increases in harms related to these drugs including addiction, unintentional overdose and death. Opioid painkiller problems in the UK have not reached the epidemic proportions seen in the US but we know that over 5% of adults in England and Wales have used opioid medicines that were not prescribed for them in the past year.
> Of more concern is that nearly all the rise in prescribing has been for treatment for long-term pain however, opioid medicines are often ineffective for this condition. About 4% of the population in England and Wales is in receipt of a prescription for opioids and once opioids are started they can be difficult to stop.
In the UK opiates are commonly used for suicide. Self poisoning is the second most common method, and opiates are the most common medication used (and opiate + paracetamol combinations are in the top 5 too). Most of these are legally obtained.