Assuming the earth is flat, how many people are part of the conspiracy
Just a thought experiment, let's say the earth is flat, looks like many professionals would know, including
Pilots/ATC/sea captain
Land surveyor and civil engineers
Astronomers and Geologists, at least the one dealing with experimental data
Militaries, at least radar operator and artillery
Just these categories are already a lot of persons, I assume I miss a lot of others. So how many person does it make in total ? 10 % of the population ?
This is a bit extreme, but maintaining a conspiracy with lots of "insiders" isn't impossible. Just think of how many people worked on the Manhattan project.
First you compartmentalize, so that only a core few know the whole picture. Then you threaten everyone involved with serious jail time for informing. (This is why we know Bob Lazar is full of shit, where he telling the truth, he'd be in prison)
It's true that secrets can't be kept forever, but they can be kept for a while.
The flaw in flat earth is not the number of conspirators, but the purpose of the conspiracy. It all falls apart when we ask why the government wants to keep flat earth from the public.
From memory, a sci-fi magazine seller figured it out, just based on address changes. He even figured out it was likely an attempt to make an atomic bomb. The USSR also had it completely compromised. The first soviet bomb was basically a direct copy of the American one.
That was also with most/all the workers in 1 location. They also had a very good reason to maintain security (grunts on the ground, not just leadership).
Some of the scientists there were communists, or at least sympathetic to the communist cause. Since the USSR was currently an ally, they leaked information to them.
Other scientists didn't follow security rules, either because they didn't care, they hated the lockdown, or they wanted a challenge. Information slipped out because of that, even if it wasn't a deliberate attempt to compromise the security of the project.
I wish Oppenheimer had spent less time on the trial, and more time on some of the really interesting scientists on the project. People like Richard Feynman, who was famous for playing bongos, trying to learn throat singing, and cracking the safes on campus just for fun. And, although slightly after the war, Louis Slotin and the Demon Core incident would have been an excellent scene for a movie.
But if the flat earth goes on, what can be assumed to be, infinitely past the ice wall (since no one really gives an answer for what's past there), think of how big maps would be! They would have to sell giant maps and make a fortune.
They're protecting the turtles. If people like Bezos knew that it's turtles all the way down, they'd certainly harvest the turtle shells to make fancy hair combs. That would spell the end of the earth.