Have you ever met someone or heard of someone doing this?
I know a woman whose husband regularly travelled abroad, fetching back beautiful presents, but after he died, she found his passport with just a trip to france on it.
He drove for a living (but had never actually passed his test) until he was diagnosed with multiple sclerosis and went rapidly downhill.
(He was spotted in an out of the way place, sitting in a cafe, eating a huge fry up, (although he was barely eating at home, and had appointments with dieticians and was prescribed build up drinks)
In short, his whole life was a lie, but she never found out why.