In the late 1930’s - shipowner Gustav Erikson was buying up the last of the sail powered cargo ships and sending them around the world to carry non-time critical bulk cargos. Mainly coal, wheat and wool. New fangled and much more expensive steam ships were carrying time sensitive cargoes and could usually be relied on to get in port on time. The sailing ships were deprecated out, lying in harbors and could be stripped for spares to keep others going at little cost. He could man them cheaply with freshly minted officers who needed “time under sail” to get the better jobs in steam ships where the seamanship under sail experience was valued. There was a finite pool of these old ships - but Erikson knew they would see his days out before they dried up. WWII terminated the idea earlier than planned and the last of the sailing ships were scrapped.
In the 2020’s - pleasure pilots are buying up the last of the “golden age” of personal flying aircraft. They generally use them on non-mission critical flights. Newer more expensive exotic material, glass cockpit aircraft are the preserve of the few or the wealthy who require reliable point to point flying without the disruptions of TSA security, airport delays and the aggravation of getting strapped in a bulk carrying tube of metal. The old GA aircraft are rotting in the tie downs, fully deprecated out and can be had for little money. Other aircraft can be stripped for spares. The instructors who teach in them work for a pittance to gain the 1,500 hours stick and rudder required to get better paid jobs in the modern fleet. There is a finite supply of these old aircraft and even if WWIII doesn’t intervene - the pool will dry up fairly soon and they will not be replaced.