It’s globally useful to eradicate/reduce disease in a region irrespective of whether or not the region’s government becomes stable. Viruses and bacteria mutate and do not care about borders.
I have no fantasies that aid will magically make countries stable.
If it is globally useful then the burden should be spread equally among all the countries on the globe. If the US is providing this service, other countries should compensate us for it.
I have no fantasies that aid will magically make countries stable.