What if a government agent approached you claiming that Earth us flat and that there is a conspiracy to hide it, and that you will be paid $1,000,000 a year to keep it under your hat.
This is even less plausible than Heiwa paying the million he owes you!
What's the logic of spontaneously bringing someone into a conspiracy and then paying hush money to keep them quiet about it?
Hey, this is a big conspiracy. It requires million, of not billions of people to be in on it. Anybody involved in math, science, or engineering would have to be in on the conspiracy. You would also have to pay off everybody involved in education of mathematics, science, and engineering. You would also have to bribe every single professor and student of every university in the world. finally, you would have to pay off the families of all these people so their family doesn't blow the whistle.
You would have to make sure the bribe is big enough so that nobody actually reveals the truth.