Another angle, The United States

The well-known American intellectual (slandered as a anti-American by politicians) Noam Chomsky famously stated that the United States was in a phase of "hegemony or survival" just before the American genocide was covered with an informal declaration of war.
It appears to me that corrupt, internationally-financed politicians destroyed the country. This is what I see as the direction of the United States right now:
Mass pedophilia and child sexual abuse for the purpose of developing disassociation
for brainwashing
Brainwashing and tight social control through broadcasting, threats and rumor mongering
Financial & Corporate Consolidation and Monopolization of industries
Absolute legal control through surveillance and corruption
Empire expansion and financing through military operations
Intellectual property theft through international intelligence operations
"Trickle down" economics, a kind of social welfare
A big emphasis on a sexual lifestyle
Manipulation of the environment for visitors, the unaware and for social control
Torture, theft from business men and uncooperative
Business & Government very close and interwoven
Very extensive international investment and involvement
Sexual tourism as an attraction for foreign business men
Heartless & Nymphomaniacial females receive brainwashing emphasis
Annihilation of competing totalitarian regimes
Control of United States soil and natural resources
Infiltration of foreign cultures

When looking at the United States through a lens, searching for weaknesses, it is clear that the enemy exploited available political positions through a long term campaign of subversion. Suddenly and seemingly out of nowhere, they used this power in an extremely abusive manner. It is likely that this was done out of paranoia, that there ties may be revealed in emerging public forums, and perhaps also out of a fears of cultural competition, especially once there privileges had been revoked. This, in combination with a lacking education (especially in politics and globalism), were the two weaknesses that caused the country to collapse.