I don't know from personal experience, but I can see how someone can have been working in a field for decades and have that profession go away due to technology change or whatever.  At that point you have a 50 whatever year old starting out all over again and the only work that they are considered for is minimum wage jobs/employers may look at the candidate and not see years of experience but instead their productive years behind them.  Someone who was a stay at home spouse until a divorce could be in the same situation.  People with a felony conviction could be in a similar boat.