Private charitable givings are tax-deductible (to an extent) so some of those donations aren't entirely, or at all, altruistic. How much of this charitable givi

Private charitable givings are tax-deductible (to an extent) so some of those donations aren't entirely, or at all, altruistic. How much of this charitable giving can be attributed to our nation being altruistic and how much of it is just the upper class choosing how their tax money is apportioned? I'm not trying to belittle your point, but is there a source that goes more in-depth on this topic?