The search for Malaysia Airlines Flight 370 failed. The airplane was not found. The search cost about $200 million. You might think that money was wasted but fortunately, a lot of good came out it. The data is an "incredible trove" of scientific information on the deep ocean. That alone is probably worth $200 million.
We know much less about the 70% of earth that is covered by oceans than we know about the Moon and Mars. Because it is difficult to map. See: https://www.nytimes.com/2017/03/10/science/mh370-malaysia-airlines-indian-ocean-seafloor-maps.html Lede: "Malaysia Airlines Flight 370 vanished with 239 passengers and crew aboard as it crossed the Indian Ocean, triggering a large-scale search for its remains that lasted nearly three years. As a byproduct of the tragedy, scientists have gained access to more than 100,000 square miles of seafloor mapped at a level of detail that provides a rare look at the ocean’s geological processes. . . ." https://eos.org/project-updates/geological-insights-from-malaysia-airlines-flight-mh370-search - Jed
