Good points, but the commonly stated objective of philanthropy is to solve entire categories of problems. You could go on giving billions of dollars to the poor

Good points, but the commonly stated objective of philanthropy is to solve entire categories of problems. You could go on giving billions of dollars to the poor just so they can get by, and eventually that money would run out, and if the people you were helping weren’t worse off, they likely wouldn’t be much better off by then. But money spent on attempting to eradicate malaria for example doesn’t have the same dynamics. There are also other forms of just regular old charity that have a similar ROI. Money spent on educating children had a tremendous ROI, so does investment in infrastructure.