the problem that these ultra wealthy people have is the size of their assets and how best to preserve their value

Ultra wealthy don't have a problem, Warren Buffet bought a railroad. It is us little guys that have a problem. We don't have enough money to go out and buy a railroad or any other ultra conservative, safe, hard assett and as such can only realistically own our own home (as much as we can afford with a small manageable mortgage). The only other assett classes would be gold, rare collectibles, and equities. Of course equities need to be carefully selected from companies with very little debt and a stong assetts vs liabilities on the bottom line. I could have mentioned other commodities, however most require lots of land for storage and most don't have that luxury.