Let's take income inequality first - we'll tackle wealth inequality later. So what accounts for the rise of income inequality in the US? Is it the increasing income share of the top one percent? Not exactly, as the following chart makes clear:

2018 - Top One Percent Not Driving Inequality Rise.png

If you don't count the income of the top .1 percent, then the income share of the top 1 percent in the US has actually gone down over the past 30+ years.  But check this out:

2018 - Top .01 Percent Driving Inequality Rise.png

It's not even the top .1 percent driving US income inequality; it's the top .01 percent!  Per Fatih Guvenen and Greg Kaplan  in their 2017 paper, Top Income Inequality in the 21st Century: Some Cautionary Notes:

“In 1981, income earned by the top 0.01 percent accounted for less than 30 percent of the income earned by the top 0.1 percent. In 2012, the top 0.01 percent accounted for over 45 percent of the income earned by the top 0.1 percent.”

So why are the super-rich getting so much richer? Next

Reference:

Fatih Guvenen and Greg Kaplan Top Income Inequality in the 21st Century: Some Cautionary Notes  NBER Working Paper No. 23321 Issued in April 2017