What technological superiority are you talking about? Outside "Silicon Valley" not all too much. And not sure if you can call Facebook or Twitter "technologically superior" anymore.
Eroding, yes, the whole infrastructure is eroding. Roads, trains, the grid you name it.
Why should a country of 330 million expect to forever have "technological superiority" over the rest of the world (population 7.7 billion)? What's more important is that technology advance and diffuse worldwide.
It's less of an expectation, and more about cause/effect. Every country wants their own military, they don't want to outsource it (by relying on NATO or Russia to protect them). So every country wants lots of money. The way you get lots of money is by capturing a chunk of the tech market. The US, Russia, China, parts of Europe, excel at this. The US enjoys being the reserve currency of the world, and having the highest military spending per capita. How did it get there? By cultivating high-tech. How did China get to where it is today? The same way.
Maybe not forever, but society benefits from better organization - in case of USA it's a democratic system - which makes productivity higher, so difference in numbers isn't the whole story.