Unfortunately, there really aren't any non-habit forming drugs as or more effective for treating chronic insomnia as their habit-forming counterparts. Insomnia is very similar to pain, anxiety, and several other afflictions in that the efficacy of its available non-addictive pharmacotherapies falls as the severity of the patient's condition rises.
Mild insomnia may be ameliorated with easily available, OTC soporifics like the antihistamines diphenhydramine and doxylamine. Moderate insomnia may be resolved with prescription drugs such as SSRIs, SARIs, antihistamines with stronger somnifacient/sedative-hypnotic properties, etc. But, like with limiting one's analgesics for pain management to only NSAIDs, the worst one's insomnia the worst one's prognosis or quality of life if they obstinately refuse to use benzodiazepines, barbiturates, quinazolinones, nonbenzodiazepines and Z-drugs, other GABAA receptor PAMs or agonists, etc.
One has to realize that every drug (regardless of its abuse potential) has an accompanying set of both detriments (addiction, dependence, abuse, or misuse being nowhere near the worst of which in terms of either severity, lethality, desirability, comfortability, or difficulty of treatment, in my honest opinion) and benefits. It is (or should be) left to the patient's discretion which pharmacotherapy has the most appealing pharmacological profile, which potentially adverse or undesirable effects are worth the risk for the potentially therapeutic or desirable effects, etc.
Most people seem to have a proclivity to greatly underestimate a drug's health risks and embellish its safety if it has a low abuse potential. Additionally, the dangers of a drug tend to be exaggerated if it has a high or above-average abuse potential. The result of which are dangerously distorted notions of drug safety which may directly cause an increased risk of drug overdoses, fatal drug interactions, overprescribed medications, and easier availability of potentially pernicious drugs because of their non-recreational effects.
The top 10, 20, 30, or 100 most unsafe drugs are not addictive or recreational drugs, but are almost entirely drugs that are easily underestimated or too easily available or too overprescribed or too commonly thought of as not being drugs.