These are legitimate concerns. With that said, the gain can still be worth those costs. Medical need must be evaluated on a case-by-case basis, not in broad generalities.

I take both a stimulant during the day and a GABAergic at night, both to help my sleep. I tried a number of supplements for several years, and I tried a GABAergic alone; while both were slightly helpful to me, my sleep still lacked any regular cycle, and I was still spending 2-3 days at a time completely unable to sleep. Extended sleep deprivation on such a scale creates an unpleasant and dangerous state. I have not had any difficulty with sleepwalking or similar behavior since beginning medication.

Not all cases are identical. Different people require different treatment to resolve the same problem. If melatonin supplements alone had helped sufficiently, I wouldn’t personally need prescription medication for this. Some individuals experience dangerous or debilitating side effects, but I have not. Supplements alone work for many others, and so much the better for them, but for some of us it is a choice between a drug with side effects and no sleep whatsoever. In my situation, the tradeoff has been worthwhile. For others, it may not be. Those affected by serious side effects do have alternative options, and often benefit from controlled discontinuation of the current treatment.

The powers in control of production (largely through government monopolies in the form of drug patents) certainly manipulate the market, but that does not change the actual risks or benefits of the chemical agents in question, though the monetary cost will likely increase (drug affordability is a major problem). If a major pharmaceutical corporation possessed a patent on melatonin or other supplements, would they no longer be a good first-line measure because of that affiliation?