Decadent societies are often prosperous but usually have severe social and economic inequality, to such a degree that the upper class becomes either complacent or greedy, while the lower classes become hopeless and apathetic. The middle class may exhibit either or both patterns, or it may vanish entirely. Poor leadership is generally held to be both a cause and a symptom of decadence, as the lifestyle of a decadent individual is usually considered to be incompatible with responsibility. Applied to the arts, decadence implies an elevation of self-indulgence and pretension over effort and talent; when applied to science and the professions, it describes an erosion of professional ethics. Individual or collective greed is generally disliked in societies with strong moral beliefs, and for this reason, societies that nurture it are sometimes accused of decadence.
Societies that persist in a state of decadence may become unable or unwilling to commit to their own upkeep and fall into decline. One historical perspective on ancient Rome is that it became decadent due to a succession of unstable emperors like Nero and Commodus. While they ruled centuries before the fall of Rome, their leadership may have played a role in its decline. This point of view may also be biased by later interpretation; beyond his unpredictability Nero was also viewed as a generous ruler and was popular with the lower class during his reign. Caligula only reigned a few years.
What wikipedia says is a perfect description of the Bush era. The American people have a higher standard of ethics and wholly different priorities. Thankfully, there are many more of us than of them.