It's the system, that helps them become this way. Most are little more than fancy looking drug pushers.
The pharmacy industry, insurance industry and doctor industry (AMA) are three arms of that system. Like a virus, they are deeply imbedded in the system and their business model can replicate readily. Society has no immune response to such a system, and as a result it causes death.
This healing system is another cause of disease of the system.
I've lost relatives due to "doctor error". I bet that almost everyone has a blood relative that they know of who was taken out by a doctor. But not everyone has lost a relative to a mob hit, car accident, or war.
They want to hook you on their dope and make you keep coming back for more. In that regard, thare are no better than the local heroin dealer. In fact, the heroin is probably safer, since it has a long history, whereas much of what comes out of the local pharmacy are new molecules which come with two paragraphs of warnings of side effects.