What evidence do you have that portion of the pie is getting smaller for most people? I do not believe this at all. It's especially not true on a global scale, where globalization has improved the lives and wealth of millions in China and India.
http://www.smashcompany.com/business/wages-in-the-usa-have-b...
The fall is especially sharp if you count health care expenditures, which have risen faster than average inflation, but since that also effects women, you could remove the "men" from the first sentence.
For specific examples of industries that have suffered, consider the decline in the wages for truckers:
http://www.smashcompany.com/business/truckers-have-seen-ther...
Men with college degrees have done better than men without college degrees:
http://www.smashcompany.com/business/is-it-useful-to-have-a-...
"The 9% cumulative increase in real US median household income since 1980 substantially understates how much better off people in the median American household are now economically, compared with 35 years ago."
When asked to agree-disagree, 60% of economists (70% when you weight by confidence) agree with this.