I think one factor that many people underestimate in the decline in any country or empire is the cost of brownfield projects versus greenfield projects. For ex

I think one factor that many people underestimate in the decline in any country or empire is the cost of brownfield projects versus greenfield projects. For example, building a new town/city and its infrastructure is dirt cheap relative to fixing and replacing existing infrastructure. This is not unlike the cost of maintaining software and refactoring it versus writing it in the first place. With a new greenfield city land, labor is relatively cheap because the cost of living is relatively cheap. There are also no entrenched interests that will engage in legal battles every step of the way. There are also no citizens whose you have to continue to support while you create the new replacement infrastructure and you have none of the complexities of migration from old infrastructure to new infrastructure. Besides their authoritarian bent, these are some of the many reasons a country like China is getting stuff done while the US and Europe gets relatively little done.