I have been toying with a concept I am calling national adolescence. My emerging theory is that civilizations go through phases much like that of a human male, and the most dangerous to all around it is adolescence. Adolescent males can do crazy, unproductive things to show off, to count coup, to bolster their ego and perceived status. They are more prone to being violent and dangerous, to pick stupid fights to prove their alpha-maleness rather than to achieve rational goals.
Nations often go through an adolescent phase. Sometimes it can last for decades or centuries. Two symptoms of this phase are 1) Imperialism and over-readiness to fight and 2) monument-building and other such show-offery.
I have written a number of times about monument building, for example here. We see it in countries trying to build record-tall buildings -- note who is doing it, they are always the nouveau riche (e.g. Dubai). We see it in cities wanting to have light rail systems in order to be considered a real city (ie as a status project). We see it in every Thomas Friedman column about China doing big things while we are not. And we see it now in the fear that somehow having China sending men into space 50 years after the US and USSR did so somehow is a marker in the decline and fall of the US.
I don't buy it. What you are seeing, what Thomas Friedman is seeing, is adolescence. We may regret lacking as much youthful vitality, but we should not aspire to the adolescent's poor judgement. Our sixties space program went exactly nowhere, except to let us count coup on the rest of the world and cement our status. The Chines space program as currently configured will achieve nothing more.
PS- The Egyptians may be a good example. All the great Pyramids were built when the Egyptian civilization was really young. There are a variety of reasons why pyramid building ended, but surely a maturing confidence in their civilization's greatness must be one.