Supercomputers have real value, in the sense that they are used to solve real problems that can't be solved otherwise Sure, and this answers the question "why

Supercomputers have real value, in the sense that they are used to solve real problems that can't be solved otherwise Sure, and this answers the question "why have super-computers", indeed, the US has several. I'm not just sure if any of the reasons you specify, all valid, suddenly become invalid when there is simply a delta between the power of US vs China systems.