There are almost 100 million people living in Vietnam. Of course the average wage is very low, currently in Saigon average factory wage is about $500 per month. Middle class Vietnamese (manager) wage is $2000 to $3000 per month. As a comparison, when i started 15 years ago the average factory wage was about $30 per month. Progress is happening. There is still huge disparity between the city and countryside.I tried to find the average wage in Vietnam, the numbers I found were nowhere near £300k... what do you do?
However, in all of Asia there are significant numbers of people, families with huge income and wealth, far more i suspect than Europe. hence all the Chinese / foreign students with properties in London etc.
I suspect a lot of the true wealth here is never officially reported or recorded.