There are two things to consider: your discount factor and how quickly the utils you generate compound compared to your money. Let's say your discount factor i

There are two things to consider: your discount factor and how quickly the utils you generate compound compared to your money. Let's say your discount factor is 3%/year. That means you have no preference between generating 100 utils today or 103 utils next year. If your money compounds more slowly than 3%, it doesn't make sense to save. Second, the utils you generate probably compound too. Contrary to what many would have you believe, the world is actually getting better at an exponential rate. Since 1981, the conditions of the world's poorest have been getting better and better. It's not totally clear, but it seems plausible that there's an exponential feedback loop involved here. Maybe an extremely poor person in a developing country has $100 of assets, and is able to increase his net worth this year by $5. With that $5, he can get a pen with some chickens or something, which will increase his net worth by $10. With that $10, he can get a radio that will allow him to hear the weather report and better tend his crops, letting him increase his net worth by $15 the next year. If you donated $30 to him, he could jump-start this process and immediately get all these gains and more, instead of having to toil for years for them. That's a somewhat farscial example, but I think it may resemble reality. Economic growth tends to be exponential, and if you artificially grow the economy by infusing it with cash, that extra boost may compound forever just like the money in your savings account would.