Noone claims that people in the third world enjoy great quality of life, for instance. You can't benefit from the advancements of others if you cannot afford them...
> I'm not even sure how this could happen.
It can always happen but it is gradual and takes time. Places like India or China were once the richest areas of the world, only to fall behind and become among the poorest later on because they stagnated while others progressed.
That is why it is partially true. There are many other factors as to great quality of life. If you have all those other factors as well then a rising tide can life your boat too. Some third world countries have seen this over the years, and others are seeing it now. Some have seen it and then something (often a coup) reverted them to bad quality of life.
Noone claims that people in the third world enjoy great quality of life, for instance. You can't benefit from the advancements of others if you cannot afford them...
> I'm not even sure how this could happen.
It can always happen but it is gradual and takes time. Places like India or China were once the richest areas of the world, only to fall behind and become among the poorest later on because they stagnated while others progressed.