Probably tucked away by some cheap bas**** who didn't want his wife to find it.
Interesting wild ass speculation, founded on nothing but your imagination.
Before you tell me why it MUST be true, my father, who had lived alone for 17 years, had $6,000 taped under his dinning room table, $6,000 in the vacuum cleaner, and $2,000 in his pots and pans. We knew where to look but never got a real clear answer as to why he needed it. He had lots of money and a Rice degree, but said he might "need to buy something" ... go figure.