The united states eventually stop supporting South Africa because : South Africa began taking arms and funds from the soviets.
Back then, United States was in the middle of cold war with the soviets union, and this showed that Soviet has implemented its influence in south africa
Hope this helps
(Jacobins group) The Jacobins killed people in an attempt to purge the public in France. They believed many people were a threat to the nation.
This is actually pretty common and the reason "why" is due to the idea of hysteria. Hysteria clouds judgement. There are so many examples of hysteria clouding societies judgement in society.