Many of them were among the smartest people in the world, and doubtless those are people who would have known it was a fake. As I said, I absolutely agree that huge numbers of people would have known. I just also think that a lot of people working on Apollo wouldn't have known or had to have known. But does some random guy working a food dehydrator count in the 400,000? How about the person who made the packaging the food went into? The person who sewed the suits the astronauts wore while in the capsules? The people who built the launch tower? Not designed, mind you, but built. They knew how to do their jobs, and they did their jobs right, but that doesn't mean they knew that doing their jobs right was required in order to send men to the Moon. In several cases, it arguably wasn't. I still don't think they did a bad job. I think they did the best they could. But I also think that there were plenty of people who had no idea how "the best they could" tied into landing men on the Moon.