I'm surprised there's a shortage, I picture being a pilot as a very desirable career that would lead to an oversupply. Is it because learning to fly is too expensive for many of the people who want to do it?
Airlines have also laid off pilots during several industry downturns since 2001. Every time that happens, some switch careers and never return to flying.
Know a few former Naval Aviators who hit their 8-10 year commit and decided to get a Masters in something not aviation related -- work-life balance was a definite draw.