That and personal choice. Son in law is 45, Has a piddly retirement pension from the local fire department. He does not have nor does not want a regular job. He spends half his time hunting and fishing and the other half in the barter economy. Mechanical work, welding, and bush hogging. He leads a happy life.
Just as I suspected. Many of the men ‘not in the labor force’ are out doing work and making money. They just don’t have an employer, and do the jobs for cash or barter.