It's important to distinguish between income inequality and wealth inequality. While related (income inequality contributes to wealth inequality), they are very different things. One's 'wealth' refers to all one's assets. Importantly, many aspects of one's wealth tend to grow on their own (eg, the value of one's house tends to appreciate). Crucially, wealth provides intergenerational security in that it allows one's descendants to start life with a 'leg up.'
With regard to income and wealth inequality:
"The OECD report finds that the richest 10 percent of American households earns about 28 percent of the overall income pie. This is a lot, but it's roughly consistent with what you see in the world's other rich countries.
By contrast, the wealthiest 10 percent of U.S. households have captured a whopping 76 percent of all the wealth in America. And that number is considerably higher than in other rich nations, as the chart below shows."
Further, the top 1% own an unbelievable 35% of all US wealth--almost as much as the bottom 95% combined.
Wealth inequality has increased dramatically of late, with the wealthy getting vastly moreso, and the rest of us slipping backwards: