Question: Considering how powerful and dangerous the Ark is, why would Indy hand it over to the United States government, instead of putting it back where it was found and to ensure it's never located, lie to them and say him or the Nazis never found it?
BaconIsMyBFF
9th Jan 2019
Raiders of the Lost Ark (1981)
Answer: To add to the previous answer, there is no way that the ark could have been secretly returned to where it was found and then conveniently forgotten. Too many people already knew of its existence and location. It would only be a matter of time before someone more sinister would retrieve it.
Answer: Indy and Marcus Brody believed that the Ark needed to be studied. They certainly didn't want to put it back where it was found. They believed that the U.S. government would find the best archaeologists, researchers, and scientists in the world to study the Ark. They are both upset that instead, the government has decided to simply lock the Ark away. This is why Indy says, "Fools. They don't know what they've got there," as he is leaving the building.
BaconIsMyBFF