Scott Sumner with a bit of wisdom in a review of Tyler Cowen’s Stubborn Attachments:

Unfortunately, when discussing redistribution, our society tends to focus on income, which is the wrong variable.  Yes, the rich might invest an extra dollar in income, thereby helping future generations.  But that’s not relevant to the real issue, which is consumption redistribution.  One commenter suggested that it might be better if I invested $10,000 rather than donate the money to a family in Ethiopia.  But that’s dodging the real question—don’t I have an ethical obligation to donate $10,000 of my current consumption? The rich should never feel any guilt about investing money rather than giving it to charity.  Where they perhaps should feel a bit of guilt is in spending $500 million on consumption, rather than donating a significant share of those funds to the poor.