[DoomSlice]

When you boil down to it, all actions are determined by what economists call "utility". People make decisions to maximize their utility. If I choose to buy a $3 Whopper instead of a $3 Big Mac, it means the Whopper is for whatever reason, more valuable to me than both the Big Mac and my $3. If I continued to lower the price of the Big Mac, there will eventually be a price to which you will be indifferent to buying the Big Mac or the Whopper. If I raise the price of both the Big Mac and Whopper, there will be some price to which I will be indifferent between the Whopper and the money I would have to pay. At that level of indifference the alternatives are said to have equal utilities.

Also, after you've eaten 1 Whopper you'll start to feel full, so maybe you won't pay as much for a second Whopper, or a third, until finally you won't pay ANYTHING for a Whopper (assuming you can't resell it). This point is called the point of zero utility (or even negative, where you'd have to pay ME to for me to eat another Whopper). This is the Law of Diminishing Returns, that the next item you consume will generate less utility than the previous one.

The same thing can be be applied to this question. There will be some price to which saving a life is "worth" more to you than your money, so you will pay so save a life. However, as the price goes up to save a life, or after you have paid to save X amount of lives, you will be indifferent to saving another life or keeping the money.

This is just the nature of humans, and there is absolutely nothing wrong with it. The generous people will just get more "utility" (as opposed to keeping the money) than the less generous will, so they will pay to save more.