I wasn’t around at the time (not quite) but America was a county enamored with isolationist ideology before getting kick started toward global hegemony with the world wars of the 20th Century. Wars that started in Europe, Asia, and the Middle East.
If America peters out as a super power then what? Will Europe, Asia, and the Middle East be leading the world in Kumbaya? Nope.
Plus, social stability is going to be frightfully tested during the remainder of this century by our rapidly unfolding climate emergency. Having a budget deficit and a piss-poor social net doesn’t really compare to the misery that’s just over the horizon of our modern industrial experiment with carbon infused dense energy as the cause of CO2 excess.