"Purpose" is also a less loaded word than "Charity", and whether you view USAIDs purpose as promoting American Exceptionalism or reducing global issues like hunger or disease, USAID was more influential than the World Monetary Fund, and often times the UN. Denigrating of this purpose in this organization is similar to suggesting a Joint Chief of the US Military doesn't really impact the world (which may be more truthful than I know if the US leaves NATO, the UN, and creates a power Vacuum in influence that other states like China fill)