It can depend on what you count as riches, in part. For example, several African countries are being enriched by oil and mineral sales, if you count wealth in currency. But several of the countries have cut very bad deals (often due to corrupt governments) over their commodity exports, so that they're exporting considerably more valuable commodities than what they're getting paid for them in currency. So if you include commodities as a form of value, net value is flowing away from the country, enriching the government's short-term budget figures at the expense of draining their long-term commodities reserves.