This Editorial Board Opinion in the WSJ reminds readers that it is the Government Accountability Office of the US itself that made these estimates of annual losses from fraud and waste.
A Government Accountability Office report of 2024 estimated the “federal government could lose between $233 billion and $521 billion annually to fraud.” The GAO report said “a government-wide approach is required to address it,” and advised that Treasury take up and “leverage data-analytics capabilities” for the job of stopping questionable payments and payments that look dubious. This was suggested as a necessary step to cut waste and fraud in a bureaucracy that is this large.