In the 3rd World, a very small number of people have a large sum of wealth. But that also does not help. Because, most of these countries including our lack financial and political stability.
Therefore, a large portion of that wealth is invested (real estate etc) overseas in countries who have much more stable economies, on top of that, most of these countries like Switzerland, UK, Dubai etc, barely query the source of income., which makes it convenient to launder money as well.
In return, it further stabilizes and empowers their economies, as wealth keeps pouring into their financial system from all over the world esp., less stable countries. And these countries barely hold them answerable to weaker and impoverished countries for the source of income invested into their countries.
And even so, the real owner of the wealth can hide behind the shell companies, as did happen in the case of Panama Leaks.
So in short, 3rd World countries struggle to get wealthier and prosperous as their wealth is dried up at home due to the reasons mentioned above.