Why less wealthy Americans have not recovered from the Great Recession?

In a recently released working paper published by the Federal Reserve Bank of Minneapolis, economists from the University of Bonn examined trends in American household wealth from the early 1970s to 2016 (the latest year data was available). They found that after taking a brief hit following the financial crisis, the richest 10% of Americans are doing better than ever before due to a booming stock market.

Why?

Poorer households typically invest in homes and other physical assets, and put little to no money in stocks. As a result, they have not participated in the post-recession wealth recovery.

Reference:

qz.com, Dan Kopf, 2018-08-07, “Half of American Households are Still Poorer Than They were Before the Great Recession”