You have a talent for assumptions.
I think the US is suffering from the malaise of late capitalism, as predicted by Schumpeter, where “mature” industries have consolidated, created connections with an expanding bureaucracy, to create conditions where it is too expensive and risky to compete. It is a condition of corporatism, where growth and innovation are stifled.
The question is whether improving technology (growth is almost entirely determined by the rate and effectiveness of technological adoption) can overcome the decadent mechanisms Schumpeter predicted so accurately. Tech is a force of its own and is very hard to stop.
In any case, this will keep the (relative) decline slow. The accumulated capital involved (human, institutional, physical) is stupendous. It will take my remaining lifetime at least to make a dent in it.
Sadly, you are the one who is making incorrect assumptions. And believe me... I wish that you were not.