McKinsey bears some responsiblity but not all of it; nobody forced people to take those opiates, the addicts also bear some responsiblity. The idea in modern society that people have zero responsibility for their own actions is part of why we're in this mess to begin with, because people with that attitude aren't going to work hard to take responsibility for their own health and wellbeing. I'd bet at least half the people here complaining about McKinsey's behaviour are the same people who'd argue that people should just trust their doctor and do whatever the doctor suggests, and refuse to accept that often what's financially in the doctor's best interests is not in the best interests of the patient's health.
Responsibility doesn’t sum to 100%. If I fly on a crappy airline and get in a plane crash, it was partly my fault, and also the fault of pilots, maintenance people, regulators, executives, and many more. If someone makes a box with a hole in it labeled “free prize inside” which chops off your fingers, it’s mostly their fault. If everyone knows that opiates are addictive, and a pharmaceutical company says they figured out how to make non-addictive ones, and gets regulator approval, and convinces doctors to prescribe their new drug, and to tell patients it is not addictive, then I think lack of personal responsibility is only one small part of the problem.
copypasta from an answer to a similar comment above:
I am not defending what the firm did but we are talking about a study that took place in 2017, it has nothing to do with what happened before and certainly doesn't account for all deaths after 2017 either.