My best friend is an OB/GYN. I've been best friends with here since we were 12. Berkeley born and bred, she is anything but greedy. She became bilingual so that she could work in a clinic in LA that serves poor Latinas. She is very dedicated to what she does. Her sister, who I'm a really good friend of also is the head ER nurse at a local county hospital. She's been doing it for decades.
I am also sure that not all are out for money, but I am sure that many of them are. I don't they they intentionally decide to keep a patient ill, I think their training just works out that way.
Now dentists....that is a whole 'nother thing. Don't get me started.