[0] https://money.cnn.com/2018/05/22/pf/emergency-expenses-house...
http://www.aei.org/publication/some-amazing-findings-on-inco...
Source?
As of 2015, U.S. 15 year olds do about average on international tests of financial litteracy, as compared to other OECD countries[0]
The issue is not that 2/5ths of people are bad at managing their money, it's that they don't have any money to manage.
[0] http://www.oecd.org/education/pisa-2015-results-volume-iv-97...
[0] https://money.cnn.com/2018/05/22/pf/emergency-expenses-house...