Why Britain is poorer than any US state, other than Mississippi

A story that's somewhat disruptive to a few narratives out there (TheSpectator):

It’s not surprising that America’s best-paid 10 per cent are wealthier than top 10 per cent. That fits our general idea of America: a country where the richest do best while the poorest are left to hang. The figures just don’t support this. As the below chart shows, middle-earning Americans are better-off than Brits. Even lower-income Americans, those at the bottom 20 per cent, are better-off than their British counterparts. The only group actually worse-off are the bottom 5 per cent.

Update: Maybe the Brits are poorer than even Mississippi (Forbes)