Someone who isn't addicted to highly addictive substances doesn't engage in risky behavior, disregarding consequences and their well-being, by seeking out undosed, more potent and potentially adulterated highly addictive street drugs.

Maybe their doctor has a valid concern. Opioids are rarely an effective treatment for non-cancer and chronic pain if taken regularly for a variety of reasons.

Ideally, if a doctor is going to stop refilling a prescription of an opioid addicted patient, they should be referred to appropriate services. Detoxification, pain management and mental health specialists should be all be involved for the patient's well-being. The patient should never be cut off cold-turkey like that.