How can I explain the Tuchman Thesis and purpose?

Generally speaking, the Tuchman Thesis is an argument put forward by the famous public historian, Barbara Tuchman. It holds that governments often make decisions that are not in their own best interests, and that misgovernment is therefore a phenomenon common to most all historical civilizations. The Tuchman Thesis maintains that government can be mismanaged in one of four ways—via tyranny, excessive ambition, incompetence, or folly. For example, in one of her most influential works, The March of Folly, Tuchman defines the mismanagement of folly as such:

the pursuit of policy contrary to the self-interest of the constituency or state involved. Self-interest is whatever conduces to the welfare or advantage of the body being governed; folly is a policy that in these terms is counter-productive.

Governments demonstrate a tendency to consistently engage in policy or international activities that not only do not satisfy fundamental objectives, such as economic growth, political expansion, social stability or sound organization of leadership but also which often times lead to their own destruction. In The March of Folly, Tuchman uses several historical examples of governments whose decisions ultimately lead to their undoing: Montezuma’s decision to court the Spanish inevitably led to the fall of the Aztec Empire; Louis XIV and the French Bourbon kings championed absolute monarchy, paving the way for the sentimentalities that produced the French Revolution, and the fiasco in Vietnam, which led to the end of American imperialism in Southeast Asia and the establishment of Communist regimes in Vietnam, Laos, and Cambodia. Therefore, at its core, the Tuchman Thesis posits that, not only do individual governments make poor decisions individually, but that this is a pattern which is invariably perpetuated throughout history.