The paradigm of working to providing money for the family or time

In work you get paid more and given more responsibility based on your experience level/years of service.  With the average length of duty at any one company being much less than 10-15 years it certainly logical to agree with the saying "learn in your twenties and earn in your thirties".  There is a disparity and disconnect in this traditional career path.  In your twenties you are paid the least and in essence you put in the most effort.  (Related reading: The Crossover Point)  In your thirties you tend to get married/have kids and your level of effort dips at work.  I ask the question why is there a dis-correlation between pay and effort?

There is a paradigm shift where they must ask the question now that I have hit my stride in my career... do I pull pack and re-configure my efforts to providing more money for my family or provide more time with my family (less time at work). 

Perhaps because many people take the "path of more time with my family" that those who chose to take the career orientated route are rewarded with higher career paths due to less competition.