The selfish folks are the people in the medical field who "terminate" patients.
I imagine that very few beneficial medical breakthroughs are made by the medical nihilists who think killing is the best answer to injury and disease.
Dr. Lifton interviewed many of the surviving doctors who participated in the Holocaust. It's amazing how ordinary they were, and how much they were like eugenicists in the US today.
They viewed their society as the patient, and disabled people as the disease. Any good doctor would amputate a limb if the patient's life depended on it. As far as they were concerned, that's what they were doing. Amputating the disabled people, so society could be healthy.
There were exceptions made for those who exhibited extraordinary talent. Their lives were spared, but they were not considered fully human.
It wasn't much of a leap to treat the racial health of society. At that time, racism was socially acceptable. It wasn't whispered about and hinted at, as it is now.
There are people today who share many of the views of the Nazi doctors. They believe that society's health would improve if we exterminated the most unhealthy among us. They believe it's selfish for an unhealthy person to want to live. Some of them believe this so strongly, that they will donate their own loved ones to the extermination program. And they honestly don't know why we find that so appalling.