Then again, it's also important to bear in mind that most common investments are made in stocks and bonds, not in workers. In this case you're investing in companies and/or government securities, not employees, so falling incomes do not necessarily imply decreased ROI.
To some extent you are right: obviously someone has to do actual work, and not everyone can just make money on investing. That said, it's not a one to one correspondance: if more people are investing, that means there's more capital available for companies to build off of, which means it's easier to get a profitable company off the ground, which leads to more economic growth.
To simplify: if you work 7 hours a day, but save 3 hours worth of income out of those 7 hours and invest it in a company in a developing economy, you could be purchasing 300 hours of economic activity. So by saving, you have actually worked 300 hours that day (without your capital, those 300 hours would not have been done at all), while if you did not save, there is only 7 hours of economic activity.
We stopped the high taxes on the rich, let the minimum wage fall in real terms, and made several other policy decisions which have caused the shift to the rich.
It's not retirees pulling us down (except perhaps arguably in the last week or two or life, drumming up huge medical bills), it's rent seeking.
However, fact is that most people's incomes have stagnated or decreased. The increased productivity is not quite enough to compensate for the increasing number of retirees and/or super rich (the article linked to by hudibras implies it's actually mainly the latter).