By definition a humanitarian is not motivated by money, so doctors are not humanitarians. This is not to say that doctors don't care about the well being of their patients, but is to say, that financial considerations are a part of every patients treatment thereby excluding doctors from the ranks of noble humanitarians who do not seek financial reward in pursuing and defining their efforts.
humanitarian: a person promoting human welfare and social reform : philanthropist -- From http://www.merriam-webster.com/dictionary/humanitarian
I don't see where the definition of humanitarian disallows a person based on their motivations. In fact, if you follow the synonym of philanthropy, you'll find that philanthropists distribute money for humanitarian projects. Where do you suppose that money comes from, if people with money can't be philanthropists?
Doctors are human beings. They have bills, debts, families, just like everyone else, and it's preposterous for you to declare that their need to earn an income makes them somehow anti-humanitarian.