On paper if you count the government surplus every Norwegian is a millionaire. And yet they often live packed into shitty apartments. The cost of living and taxes are much higher.

And what has that to do with the numbers of millionaires being a lot higher there then in the US?
btw. AS far as I know housing prices in the US are worse.

61 out of 100 U.S. households will break into the top 20% of incomes (roughly $111,000*)

Households is not people.
Income is not wealth.

And that headline looks awfully like some statistic massaging. I can't say because the website does not let me in (EU).
I guess to say that 61% of households are stuck at the lower 20% for at least 2 years would also be right. There are not that many university students that make much money while studying.