These countries have the citizenry usually unarmed, while the military is usually highly homogeneous (usually ethnic and class unity within the military, and fiercely loyal to their masters).
Many of the citizens and residents that would benefit from material conditions improvement are also some of the least connected to the land, as they are usually immigrants whose families are elsewhere. They would not be protecting their families in any conflict, and would not benefit from the improvement to the lives of legal citizens.
It just seems that the periphery is better equipped for revolution, and Maoist third-worldism is more correct at analyzing the world. But maybe I am going about this analysis completely wrong, so please feel free to correct and link me to resources. Thanks guys