a fool at 40 is a fool forever
a fool at 40 is a fool forever
proverb Someone who reaches middle age and continues to act foolishly is unlikely to start acting more maturely. A: "He's way too old to be spending his money so frivolously." B: "I know. A fool at 40 is a fool forever."
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.