Gary North says that “Empires take time to develop, and at some point, they drain the financial resources of the nation that launched the empire. There are no exceptions to this process. Empire always produces bankruptcy.”

This is because empires are not undertaken in response to a need.  They serve as a wealth transfer from the taxpaying masses to the special interests that are needed to expand and run an empire.  The winners are the financiers of the empire, weapons makers, bureaucrats that run the empire, military people who enforce the rule of the empire and get neat looking ribbons and medals, think tanks, and so on.

The masses pay for the empire and the salaries of those who run it, and pay for the weapons and soldiers to control it, and supply the soldiers to die for it.

But there is no market being satisfied.  The wealth transfer and capital misallocation and destruction needed to acquire it and maintain it eventually destroy the empire from within because it makes the majority poorer and corrupts the government.