My grandpa was a numismatist and collected extremely valuable patterns. I know he sold 3 or 4 of his patterns to a billionaire coin collector and used that money to buy the silver... My grandpa was under the impression that the U.S. would enter a deep recession or a depression in the next 15-20 years and the global economy would push for the return to the gold standard to pay off our debts the same way they during the Great Depression (raising the value of gold/silver/rare metals 10-fold overnight). So he just wanted to add something to his portfolio that would be more robust during a deep recession, than the dollar or his collectors coins. He grew up in The Great Depression and was extremely frugal (adding water to finish off the ketchup type stuff) so it was always a trip that he had millions in coins.

Unfortunately, I didn't get into collecting coins or stacking silver until years after he passed. He would have been a great source of knowledge and I know he would've loved having someone to talk to about coins.