Why is the Italian 1911 50 Lire Gold Battleship coin so hard to locate?

My guess as this celebrate both the fiftieth anniversary of the Kingdom of Italy- and the golden anniversary of the Royal Italian Navy- hence the Battleship theme- they were grabbed up by seamen, Naval officers and vets, and kept in the family much like such heirlooms as war medals or campaign decorations. They circulated widely among the Navy men, and were probably given out or sold at a slight premium on Veteran"s days ( I know that holiday did not exist in l9ll but Naval Patriot"s day) or something like that did) I have only seen the elusive Four Stack Battleship coin in catalogues such as the Yeoman books. I have never seen one in a coin store! No they did not voyage into the Bermuda Triangle- just rare and closely guarded. No US Gold piece ever depicted a battleship or other war vessel to my knowlegde- Columbus ship on the Columbian Half dollar but not on Gold coins. it"s a rarity, and they seldom surface, no pun intended. Even rarer is the l907 Prova commemorating the allegedly lost and secretive PROVA ( proof, Test) Expedition. These were made in 50 Lire and l00 Lire sizes the latter being larger than a US $20 St.Gaudens- who was a sculptor and not a Holy Man! by the way.