I think that is the turning point of losing your sanity
No doubt time takes its toll. I'm thinking most expediters are probably older ( 45-55 years old) when they start in this industry compared to the average age of new entrants in other lines of work. Given they are older from day one, they are working with a shorter time horizon.
This industry is not kind to young folks in particular. Expediting is not very conducive to those in their 20's and 30's who are just starting marriages and new families. Naturally, they want to be home more often, and who can blame them?
The flip side of the coin is folks a little older are usually empty nesters with the time, patience and maturity to adapt to the expediting lifestyle. I don't have any statistics, but would venture a guess that most under-35 years of age last less than one year in expediting.