It certainly is not the obligation of the rich countries to help the poor monetarily, unless the rich county is at fault for the state of the poor country. On the flip side, it is generally wise to "aid" in the development of impoverished economies.

almost all monetary foreign aid is just positively spun bribery and is rarely in amount large to make a serious difference in the receiving country. It is entirely possible that foreign aid can prop up bad governments, especially military dictatorships.

Most non-monetary aid just prolongs bad situations. The aid is either "requisitioned" by the government or helps keep the population content enough not to revolt en masse against the situation.

The only positive cases of aid are of limited duration or infrastructure improvements.