How is it any of your business if I want to destroy my kidneys or kill myself? Now, you shouldn't have to pay for this if it happens, but my body is my own responsibility to care for, so how as a society do we get off telling people how to care for themselves?
This is a specious argument. Unless you plan to sit at home and die quietly how exactly is the ER physician supposed to determine if you did this to yourself or not? The concept works okay in theory but fails to be even slightly practical or implementable. Unless the idea is to just let the ER physician decide on their own accord who they should or should not treat.
As a society we don't tell you how to care for yourself. As long as you are 18 and of sound mind you cannot be treated against your will. Nobody can force you to see a doctor, take any medication, or anything else. If they do treat you against your will in most places that's at least assault.
You can see an MD, DO, PA, DDS, NP, acupuncturist, aromatherapist, shaman, voodoo doctor, crystal healer, televangelist or anything else that floats your boat.
What we do say is that the average person does not understand pathology, physiology, pharmacology, and pathophysiology to make complex judgments about the medication they should be taking. (You do get to make simple decisions assuming there are reasonably safe drugs to treat the problem like NSAIDs.)