Earlier quoted context omitted.
You seem to equate hard work ethic with sustainability, this is false. You obviously have never experienced the joys of winters with nothing todo except read, learn, cook and play, because you worked insanely hard on the farm for 6-8 months of the growing season (being your own boss, but who cares about that).
A friend of mine is a farmer -- typical Wisconsin corn & beans. Those winters are spent finding other income sources. Some of his activities: Driving the big snow plows. Short haul truck driving on country roads in the dark. Repairing his ancient equipment. Being a local dealer for something or other. Same with any time slot that he can fill during the growing season. An issue he faces is that he pays more for seeds…
OTOH, my grandfather, who worked his own farm until he was deep into his 80s, is just about to celebrate 102. Up until a couple years ago he was still taking stairs two at a time, and winning corn shucking contests. Would he have made it so far, or in such good shape, if he had spent his life at a desk?