Every digital ad bought today is paid for under the assumption that something on the other end is human. That assumption used to be defensible. It isn't anymore. Ad fraud is projected to cost brands $172 billion globally by 2028, up from roughly $84 billion in 2023 (Statista, citing Juniper Research). About 22% of global digital ad spend is currently lost to fraud. The Imperva 2024 Bad Bot Report found that 49.6% of all web traffic is non-human — 32% malicious bots, the rest benign automation. The ANA's programmatic transparency study found that $20 billion of the $88 billion programmatic ecosystem is waste, much of it Made-For-Ads sites that detection vendors have not been able to shut down. Those numbers don't reflect a detection failure. They reflect a structural one. The detection layer has been losing for years. LLMs are about to make the loss permanent. How detection currently works The major fraud-prevention vendors — DoubleVerify, Integral Ad Science, Human Security, Pixalate — operate in two stages.…