Some of the richest countries in the world are filled with desperately poor people.
Having oil, copper, gold and other valuable resources does not translate into healthy economies.
Simple: The wealth that is generated by these resources is stolen by a handful of local elites who cooperate with foreign looters.
The offshore banking system facilitates this theft and if the local complain - or have the temerity to keep the profits for themselves (think Iraq, Libya, Venezuela etc.), they are dealt with by other means.