Maybe whenever you hear those stories about a famous work of art being stolen and later recovered, they've actually just stolen the forgery and the galley just puts up a new fake one.

The robbers then can't sell it because they have a worthless fake and the 'real' one is clearly on display in the gallery, and they can't expose the fraud because then they'd out themselves and go to jail.

The perfect scam!

That's what they do with a lot more paintings that you would think. Not because they don't want the plebs to look at them but because being exposed to the environment would cause irreparable damage to it. So they have experts make recreations and display those.

This isn't really a conspiracy theory is it? I thought it was something they were open about that they often have replicas on display for security/preservation reasons