Warren Buffett. Berkshire Hathaway has over $300B in cash reserves, Buffett owns 15% of Berkshire and directs investments — he chose to park all that value in cash reserves, roughly $50B of that is his share.
From this article in 2024: https://markets.businessinsider.com/news/stocks/warren-buffe...
There is additional context there explaining why Berkshire holding cash reserves is unique to their needs, and historically has only represented 17.5% of their total assets.
Billionaires and large firms are not sitting on piles of cash Scrooge McDuck style, because holding cash is costly.