The problem is more complex than it appears
More specifically, there is no shortage in raw materials and natural resources. Whatever natural resources market you may look at, it is saturated with plenty of suppliers from different countries undercutting each other. The implication is that it doesn't give them any advantage as any of them can be easily substituted by another supplier. Apart from that, such countries have corrupt governments which are busy filling their pockets. They are not willing to improve the lives of their citizens as these citizens may no longer want these governments once they are better off overall
What you said expresses exactly what happens in Brazil.
Corrupt politicians tool everything, and the population experiences a lot of social inequality.
Banks dominate the economy, set abusive interest rates, and end up indebting the population.
Our minimum wage, in theory, should be adjusted annually to keep up with inflation, and today we have a salary of R$ 998 while the correct salary should be approximately R$ 4500. It is ridiculous, a country with so many resources, and so productive, to be so weak economically.
In my view, what makes the development of a country most difficult is the concentration of income and the social inequality caused by it.