AI models still make up facts, even when trained on clean, high-quality data. This is not just a data problem. OpenAI’s own research shows hallucination comes from how models are trained and scored, not from bad inputs alone. Benchmarks reward confident guessing over honest uncertainty, so models learn to bluff instead of saying “I don’t know.” This piece breaks down the real causes, shares real-world consequences, and gives simple steps to catch AI errors before they cause harm.