Everyone who proudly mentions the fixed pie fallacy usually ignores that a lot of "truths" in economics: a) Make sense only at an aggregate, whole economy, sometimes even whole world level. b) And doesn't happen instantaneously, leading to the famous Keynes phrase: "In the long run, we will be all dead". c) Are defined in very simplified models and require a lot of premises to hold, for the results to be valid (the also famous: "All else equal").

Also, your examples of help are way more broadly defined than what the parent poster is talking about. It takes a stretch of imagination to classify the fact that people are working for wage to make sure I have water with specific programs that give arbitrary groups some advantage, even when this is done with the best possible intentions.