This [1] is a study I read some time back that broke down the numbers. The paper was focused on the chiseling out of the middle class, as is this one. For instance in 1979 the middle class controlled 46% of all income, and the upper/rich classes controlled 30%. Today (well at least today as of 2014) the rich and upper class control 63% with the middle class left with 26%. There's even been a chiseling out of the middle class as a whole declining from 38.8% of society to 32% of society.
But the eye opener is this. This is the change in the size of each economic group between 1979 and 2014 as a percent of the total population:
- Rich: 0.1% -> 1.8%
- Upper Middle Class: 12.9% -> 29.4%
- Middle Class: 38.8% -> 32%
- Lower Middle Class: 23.9% -> 17.1%
- Poor or Near-Poor: 24.3% -> 19.8%
Since statistics like this are certainly subject to biased interpretation and 'massaging', this [2] is a wiki section on the political stance of the Urban Institute. In any case though the paper is very readable and methodology very transparent. I found it all eye opening to the point that it actually changed my worldview. America is doing something very right economically. Note the increase in the upper middle class is more than double the decline in the size of the middle class meaning in that time period you also saw people moving from poor or lower middle class to upper middle class.
I'd hypothesize that what you're seeing is simply less of a bubble. 15 years ago the internet was much more of a luxury and the individuals using it were reflective of that. Now it's ubiquitous and the class distributions are much more balanced.
[1] - https://www.urban.org/research/publication/growing-size-and-...
[2] - https://en.wikipedia.org/wiki/Urban_Institute#Political_stan...