Hundreds if not thousands of people would have to have been in on the conspiracy if the Moon landings were faked. Think of all the engineers designing, testing and operating all of the vehicles and providing all kinds of support. And all the people that would have been involved in the fake videos, fake photos, etc. And yet, to this day, not a single Apollo official has come forward to reveal the "truth" about the fake missions. Wouldn't you think that at least one person on his deathbed would say, "Before I die, I have to tell the truth. We faked the Apollo program." Nope, not a single one.
Every day in the United States top officials leak information about important things. Look at Edward Snowden. Or Deepthroat from Watergate -- that guy's leaked information brought down the President himself! Yet somehow, out of thousands of people that would have been in on the Apollo conspiracy, not a single one has leaked the "truth" -- not even anonymously. And this is what flat earthers believe.