In a rambling essay, I looked at the question of whether a good person could be a billionaire. I concluded that, in general, the two are not compatible. The gist of the argument is that if a person is good and they have vast resources, then they would use those resources to do good. I, of course, also used an analogy: could a good person on a derelict ship sit on a vast trove of supplies while other people suffered and died from a lack of supplies? The answer would seem to be obvious, a good person could not do that. In thinking a bit more about this matter, I realized I had omitted some important ethical considerations.
In moral philosophy, philosophers make an important moral distinction between doing harm and not doing good. As philosophers such as Mill have argued, our intuitions tend to favor the idea that people do have an obligation to not do harm to others. That is, we generally consider harming others to be wrong—although there can be exceptions. So, a billionaire who becomes rich by doing harm to others or who uses their wealth to cause harm would seem to be a bad person—or at least not good. But one can make a case that people have no moral obligation to help others and can withhold their assistance and still be good.
Immanual Kant considers just such a scenario in his moral philosophy. He asks us to imagine a person who is very well off and could easily help people. This person considers their options and elects to not harm others but also decides to withhold all assistance. Kant considers that such a person would be more honest than those who speak of good will and charity but do nothing to help—this person makes no bones about charity and good will.
Kant being Kant, he believes that this person would be acting immorally. Interestingly, Kant uses a method that I call reversing the situation: he asks us to imagine what the person would want if they found themselves in dire straits and in need of assistance. Kant claims that the person would want the help of others and thus he cannot will the moral rule that no one is obligated to help others. Crudely put, Kant seems to be arguing that since if a well-to-do person found themselves in poverty, they would want help and thus the morally right thing to do is to help others. That is, to do unto others as you would have them do unto you. The Golden Rule. This sort of reasoning can, and has, been countered.
One hard core approach is for a person to insist that they would not want such help; that if they were poor or otherwise in need, then they should be left to pull themselves up by their bootstraps. This is, of course, easy for a well-off person to claim. But even if it were true that they would refuse such aid, this is not decisive: what some people would or would not want does not seem to suffice to show what is good or bad. This also applies to Kant’s case: even if everyone would want help, this seems to be just a fact of psychology rather than proof of what is right. That said, the reversing the situation/Golden Rule is a good start and can be very useful in considering the morality of actions. After all, thinking about why you would not want something done unto you can help in sorting out why you, perhaps, should not do it to others.
Another classic distinction in ethics is between killing (or doing harm) and letting die (or allowing harm to come to others). In the case of the billionaire, if they acquired their wealth by or used it to cause harm, then they would be doing active harm and thus would not be a good person (in general). But if they merely allowed harm to come to others, then one could contend they are not doing wrong—they are merely allowing wrong to occur. Going back to the ship analogy, if the person is killing other people and taking their supplies, then they are doing wrong actively. But if they merely sit on their vast stockpile, they are merely letting people die. One could argue that a good person could do this, since they are not doing evil.
One can, of course, argue that letting people die can be doing active evil. In the analogy of the ship, the person who stockpiles the supplies is actively denying other people what they need to survive—they are killing rather than letting die. Likewise, a billionaire who stockpiles wealth is denying others what they need—thus they are actively doing harm. To use a more extreme analogy, think of a derelict spaceship and imagine someone who is stockpiling air so that they have a vast supply they can never use up. They are thus actively killing the other people on the ship by taking away air that they need. They cannot be a good person and do these murders. Likewise, a billionaire is actively harming people by taking away resources.
One could, of course, argue that there is plenty for people—if they would just work hard and pull themselves up by their bootstraps. But that is simply not true; a person cannot be a billionaire in a meaningful sense unless other people are poor.