The main forcing function is gravity. The second function is FAA regs. Third is that most, but not all, pilots will not fly on aircraft that are out of mainte

The main forcing function is gravity. The second function is FAA regs. Third is that most, but not all, pilots will not fly on aircraft that are out of maintenance schedule. The universe of owners/operators that disregard the above is frequently the cartels or other criminal orgs. The aircraft can also be used as a source of scrap parts, (IE, another person owns the same aircraft and wants to replace components that are no longer in production, so they buy this one), or it can be scrapped itself and used as say, a burning man art car, or a feature at a cool airbnb somewhere.