Like cannabis, people who use ketamine as an escape/coping mechanism can become habitually addicted. Ketamine addicts exist; two of my friends fit this description. From their reports, the first month off of the drug is a white-knuckle experience. If any becomes available, they can't resist using it until it's gone.

A lack of physical dependence should not be interpreted as addiction-proof. Nobody is physically dependent on gambling, for example, but gambling addiction is prevalent.