I'm not following or buying the consumption of resources concept either. (But am pretty sure I gave back far more than I used up at any rate
). I've certainly heard that medicine doesn't like to poach people from other health fields (i.e. nursing), which makes sense, but I'm not sure why medicine would have the same desire to protect the legal profession. And not all professional training is a financially draining exercise; it probably costs medical schools more money than the tuition to mint a new doctor, but I doubt that's true for law, business, etc. And maybe the distinction is people who have trained but not worked yet???
At any rate, I think that one's advanced degree could be looked at as an asset or a liability, depending on whom interviews you, and how well you can spin your past experiences. People who are coming from a non-cookie cutter (i.e. 3.5/30 bio major right out of college) mold often have to do a better job of selling themselves, as they are difficult to compare with the hordes of other applicants. Their distinctions can make them stand out positively and add class diversity or can hurt them negatively.
It will all come down to your reasons for the change, and your "back story". Schools don't want to hear that you made a mistake on a whim, went to many years of grad school, and now have decided that you misstepped and want to try medicine instead. That kind of candidate concerns adcoms, as they worry that the person will be in the same position in four years applying to some other discipline. You need a back story that suggests other than a career student or someone who is still finding themselves (at the expense of a professions resources).
As an aside, I would suggest to the prior poster (NJBMD) who is an MD now looking at JD programs that the JD adcoms will necessarilly have a lesser concern about prior careers then med school adcoms, as unlike medicine, law schools do not consider themselves to have a "gatekeeper" of the profession role or obligation. Law schools will let in as many people as are financially feasible for such school, and leave it to the state bar (and employers) to regulate the number who actually get licensed and allowed to practice (the weeding out occurs after schooling) -- in medicine, the number of people let into med school is closely limited and it is expected that a very high percentage of those entering will become licensed residents and then practicing physicians. In most states (with some variation) I believe around a third of the people who take the bar do not pass. And most law school advisors happilly espouse the multitude of non-law type jobs one can also do with a law degree. So the experience of applying to law school isn't exactly going to be analogous.