Some of the opinions in this thread are quite harsh, no? There's a lot of stigmatising of addicts and blaming of addicts which I don't find to be particularly kind or agreeable. Addicts are not to blame for the failures of the system, or for their circumstances, but do still remain responsible for their own actions. All those things can be true.
Anyway... I don't think this will have any bearing on ketamine therapy for depression, because ketamine therapy is a relatively new phenomenon that has grown in popularity παρά the bad press around ketamine that very much already exists and has done so for decades.
There are certain countries where it's relatively rare or difficult to obtain so maybe the dangers are not as well known. However, somewhere like the UK, not so long ago it was legal, cheap and easy to obtain, and poorly understood. A lot of people got addicted to it and didn't know they would do significant damage to their bodies as a result. It made people very sick, because in large quantities consumed regularly it's hugely damaging to the bladder, liver and kidneys (especially the bladder) not to mention the damage to the brain (I know less about that, I just notice the change in someone who is addicted).
It's notorious in the UK and was more and more regulated, the price went up, it decreased in quality, was cut more etc. yet still ketamine therapy has become popular, research has continued, and the benefits are apparent. It's still relatively easy to obtain now, it probably wouldn't take someone savvy enough very long to find some in a reasonably large town with minimal effort. Ketamine has been a popular street drug here since the 90s, and it was around the 2000s where people started to learn of how dangerous it is when mishandled. In fact, an acquaintance of mine drowned as far back as around 2010 having taken ketamine, walking home on a night out.