The best example I have of the do-gooder act that had horrible consequences is the elimination of DDT. It later proved to be a false theory of DDT harming pelican eggs, so the DDT ban did no good. The bad was the elimination of the only powerful medical treatment for lice, bed bugs and similar gerridae. The horror was the elimination of the best mosquito treatment and the subsequent spread of malaria which to date has killed tens of millions of Africans.
The neo-Conservative movement is probably the most powerful indigenous American intellectual movement. While we have generated an indigenous pragmatic philosophic movement and a Transcendental poetic/psychological movement... neither have had the global weight and consequence of the neo-Conservative movement.
Nearly everywhere in the world, when nations seek a
new path to escape famine, to develop national sanitation and health
and to create vigorous economic growth they look straight to the ideas
of America's neo-Conservative movement.
Summary: Do-gooders are usually ineffective, often do great harm and some of the people who have studied do-good projects became the core of the globally successful neo-conservative movement.