Yeah I would consider pet owners and people with depression (so groups of people that benefit from this specific tool) a part of general public, both are fairly large groups.

And ketamine is employed by trained professionals appropriately in veterinary hospitals and psychotherapy contexts. The public does not need unregulated access to ketamine for this to happen.

Computers are employed by trained professionals appropriately in military contexts. The public does not need access to computers for this to happen.

There's no task I cannot complete without ketamine, except for the consumption of ketamine itself. Without a computer I cannot perform my job, nor basically perform any modern professional job.

This framing is terribly paternalistic. If a person is taking a drug, they themselves are who is possessing and using it. They aren't some mere passive subject for doctors to be acting on. Furthermore, they shouldn't be forced to convince some doctor-bureaucrat they have some specific medical condition, or even a "medical condition" at all, to be allowed the treatment they'd like to try.

Even so, I don't believe it deserves to be on that list. I consider responsible recreational drug use a clear and valuable purpose in its own right. It doesn't inherently lead to individual, much less societal harm and it allows individuals to experience and explore various states of human consciousness, an extension of the fundamental right to bodily autonomy.