I am always amused by this proposal. Who would BUY the Vatican's "treasures"? Some billionaire, of course. Would this billionaire make the treasures available for viewing by the public, as the Vatican does?
And the moment Mr. Billionaire bought the stuff, wouldn't the cries start immediately: "Mr. Gotrocks should sell the treasures he bought from the Vatican, and give the money to the poor!"
And suppose Mr. Warbucks buys the Vatican treasures from Mr. Gotrocks? Well, then. "Mr. Warbucks should sell the treasures he bought from Mr. Gotrocks and give the money to the poor!"
Ad infinitum.
The only solution to the problem created by the existence of treasures like the "Pieta" and the Sistine Chapel is to smash them.
Most importantly, once a full-scale liquidation is complete, and 10 billion, or 100 billion is raised, and even distributed, what do you have left? More importantly, what was accomplished?