Mach - what does your post have to do with the facts in the OP that the wealthiest 1% own 42% of the nations wealth and the next wealthy 4% own an additional 27% making a total of 69% of the nations wealth owned by only 5% of the people here?
It points out the irrelevance of the fact, and, how it's misleading.
Mathematically, it's normal and expected. It's not following individuals, so it's only a gap between 0 and near zero earnings, and the very highest.
Given population growth, and global expansion, and ever-increasing opportunities to access larger markets that young kids can jump in and dominate (see facebook, google, yahoo, etc.), the top is and should be increasing dramatically. So take any time today, and 20 years from now the bottom earners should be fairly flat, relatively close to 0. Those earning the most, should be some percentage of the overall markets, which are ever-increasing(*). Again, it's not individuals, so only if you keep doing the same job, for the same wage, your entire life, would this be relevant.
Put more simply, if you earned nothing twenty years ago, and earned nothing today, you'd have flat income growth.
If you instead grabbed 10% of the video game market via business venture 20 years ago you'd get $500M in revenue. Holding that share you'd then have 4x that, or $2B in revenue.
Assuming you get compensated in some way based on percentage, what happens to your income with respect to the $0 earners (or near 0 such as min wage).? And since that is not a figure based on individuals over time (the gap is not following the same people), it doesn't prompt any call to action..other than today is better than every before to participate in world market growth (well, not today, but you get the idea).
A far more comprehensive analsyis can be found here that takes into account entitlements, size of the brackets, and work:
Two Americas: One Rich, One Poor? Understanding Income Inequality in the United States
The remaining inequality in society is heavily influenced by the lack of work at the bottom. If working-age adults in the lower quintiles worked as much as their higher-income counterparts, the income disparity of the top to the bottom quintiles would fall to $2.91 to $1.00.