But GDP is a measure of income in effect, not wealth
Over time of course higher GDP per head means the country is richer, but what really matters is the income at all levels not the GDP per head if there is significant distribution disparity
Our issue is mainly distribution of wealth and income.
You also need to consider GDP PPP really and not simple GDP (PPP adjusts for cost of living)
For extreme version see Saudi GDP PPP per head and their distribution. They rank 1 above us in regards GDP PPP, and yet the wealth divide is massive.
Wealth per adult
en.wikipedia.org
Take note of the gini coefficient for demonstration of UK being quite similar to most western nations, but not as close to silly high numbers as USA and Saudi (and Russia, particularly high as you would expect)