I was just thinking of something that may apply here, lets call it the "Damaged Beyond Natural Repair Threshold ". If we choose to live or are raised with a certain lifestyle that is damaging to our bodies, then at some point the body will be unable to self-repair this damage. I realize this threshold may be blurry or transitional, but I believe the body/mind can only be put through so much stress until it breaks. Once someones passes this point then they will require the help of doctors, medication, surgery, etc. No amount of Tony Robbins tapes will help them once they cross this point, although it wouldn't hurt
I have no idea how we determine if someone has crossed this threshold...I'm just a simple-minded engineer.
Of course people can be born "broken" as well, or are genetically at a higher risk for diseases.
The whole thing seems really tricky to me--I do not envy the decisions the doctors must make.