Conqueror's Curse:

A condition where a conquering tribe or group dehumanizes themselves and commits horrific atrocities in order to acquire or wrest territory or resources from an existing group. Then, in order to make what the conquering group did seem normalized or 'virtuous', that group engages in deep mind trickery, and historical revisionism, as well as engage in delusions of superiority. Descendants inherit this pathology and may get defensive or play games with the truth. However, this act of self-deception then in turn sows the seeds of narcissism, delusional thinking, magical thinking, and other dysfunctions of judgment such that it plants the seeds of the conquering group's downfall. The rest that follows is simply a matter of time.

Cases in Point: White people in America, & The State of Israel

Update: Chris Hedges on The Downfall of The American Empire