The literature disagrees. The causes of addiction are complex, but are broadly based in factors that are reasonably considered 'instability' in the colloquial sense. These include things like adolescent abuse, SES, disengagement from 'conventional' society, mental illness, etc. There is a genetic component, but its contribution is relatively modest.

The trope of a well-functioning adult succumbing to the allure of drug abuse is a red herring.

https://sci-hub.tw/10.1080/09595239996329