That’s investment, carries risk, and involves work and worry. He was a saver. Both are good practices. He was beyond frugal, he was cheap, but a lot of people who did not have much growing up are frugal. Some go the other way, have no idea of how to manage money. Ben Coates had six children with five women in his first year in the NFL. (Took care of his spending habits, I am sure.) He was shocked! Shocked I tell you! To learn how little he made as a high school football coach after his playing days were over.
Well I assume he wasn’t putting it in a mattress, he had to be investing it somewhere.