Self medicating drugs with high abuse potential is very risky. Having tightly controlled doses, intervals between doses, settings for administering the doses can offset much of the abuse and addiction potential.
Like everything else in life, upsides have to be weighed with the downsides. For people who can't afford clinical ketamine treatment and are depressed, I don't see anything wrong with just buying some ketamine on the black market.
Opiates on the other hand, that's a different story.
This fear mongering on "freedom to use what every you like" should stop. It serves no purpose but keeping prisons full and street drug in bad quality. Why would we want to pay so much tax for that?
Every politician who claims to be in favor of "freedom", but cannot deal with the freedom to use what ever you like is a fraud.
Granted, but is it more or less risky for a person to remain severely depressed, if regular medications don't work?
If we think ketamine therapy will soon be covered by insurance it may be lower risk to wait.
Anyway, do you have a source for that?