Some reactions to my "a classical ethical bind for lawyers" post suggested that the ethical question was easy: The lawyers whose client had said he committed a murder should have revealed that information in order to free the person who was wrongly imprisoned for that murder, even assuming that would have meant disbarment or long-term suspension for violating lawyer-client confidentiality. If they didn't do this, they'd be acting unethically.
But even assuming that the underlying confidentiality rule is unsound, surely it's not so clear that people have an ethical duty to save another's life at such great expense. My guess is that if you spent $10,000, you could likely save the life of some sick child in Africa; if you spent $50,000, I imagine this would be even likelier (and perhaps the number is actually a lot less). If you donated a kidney — which will expose you to a roughly 0.03% risk of death, and a slightly larger but still very small risk of complications — you could dramatically reduce a roughly 20% or more risk of death for someone on the kidney waiting list (since that's how risky it is for him to be on long-term dialysis while he's waiting for a new kidney). If you find someone who's near the tail of the waiting list, you might reduce a still greater risk. Yet most of us wouldn't say, I think, that it's really your ethical obligation to run such a risk, or bear such a cost, to save a stranger's life.
Likewise, I don't think that it's really your ethical obligation to lose what is likely hundreds of thousands of dollars in future income, by giving up a profession that you spent over a hundred thousand dollars to train for. You might deserve credit for making such a choice (assuming we conclude that the ethical rule you're violating is indeed unsound). But that's different from saying that you have an ethical duty to make that choice.