For $10,000 a day you could save 100 lives a day via optimal philanthropy. At a certain amount of money, you might have a moral responsibility to not do exactly what you want to do. http://www.givewell.org/international/top-charities/villager...
Also: Fuck slavery. Nobody has the right to my life. I'll help the poor, but it isn't because I'm responsible for them, it is because I can empathize or sympathize with their condition and the relative cost of helping them is negligible.
"There will always be something more you could do for others no matter how much you give away." This argument becomes irrelevant once you boil things down to a question of preferences.
Eh, no. Nobody has any moral responsibility to live their lives for someone else's sake.
Pull a toddler out of that path of a bus - I'm not sure, I think so, but I'm not sure; I don't have a rational reason for it that can be derived from my moral axioms. I don't care very much either at this point, it's a different discussion I think (or at least a discussion much further down a sliding scale). For the case presented, I do have a strong opinion about, and felt offended at the thought that someone would suggest there is such a responsibility. Which is why I responded.
In the case presented, the only differences from the toddler's are the time required to save the lives, and the psychological availability of the lives saved.
Unless your moral intuitions and/or moral axioms allow lower levels of responsibility for suffering which is easier to ignore, the "time required" is the only escape.
If you lived in a world where toddlers were perpetually falling under busses in front of you, would you be morally obligated to stay in good physical condition and pay attention to nearby toddlers so you could save more of them? If not, you should be safe from the responsibility to maximize your income and use the surplus to save lives.
Pretend I said "something like a moral responsibility" or "an important intuitive one sense that one action is better than another action". There is no such thing as a moral responsibility.
In this light, the parent post is right. "You might have a moral responsibility" implies that you may feel compelled to do something. The frequent misinterpretation is that you have a responsibility to someone else, which is false. If you feel compelled to carry on a job you hate to save lives, you have a moral responsibility. If you do not feel so compelled, you do not have a moral responsibility. You cannot have a moral responsibility without feeling compelled.
Oh this is very much a contested position (known as 'objective' vs 'relative' morality). If I feel that murdering people with red hair is morally neutral, or positive even, is it so? I posit that it's not - murder is objectively morally wrong, no matter the ideas or feeling of being compelled of anyone.
To phrase it in your terms, I think everybody has a moral responsibility not to murder people, even if they feel compelled to do so.