Depends on where you live in the U.S. There are big differences between regions, states, metro areas, etc. I know many rural areas aren't doing well and have lower incomes, BUT, their cost of living is very low. I doubt if this 'study' took this into account. $300,000+ can go a LONG way in some parts of the U.S., especially rural areas of the south and midwest where the economy is particularly poor, but the cost of living is very low. $300,000 would be worth far less over-all in places like Vancouver or say Boston, where I live.

Where I live [Boston] the metro unemployment rate is 5%. The state unemployment rate is I think something like 6.2%. It's the rural part of the state that's really hurting, but this has been true since before the 2008 collapse.