The fall of the US will absolutely harm other western countries yes. But we will build and eventually thrive, unlike the US if it remains on its current trajectory.
I'm sorry but that's such an odd statement. One of the reasons people are saying that the US is currently falling or something is because they aren't as keen on defending Europe as they once were. The point is that Europe cannot even realistically defend itself.
Euro nationalism is so weird to me. I can't think of any metric where the US is doing worst (a part from healthcare and other social issues but those have always been worse in the US). Like in what way do you think that Europe is somehow stronger than the US? By the way this is coming from someone who isn't american, it's just weird that you actually think that Europe's trajectory is somehow towards a thriving future but the US is on its way to fail.
I remember the same doom and gloom and boasting from Europeans back in 2016, but it turns out that even with Trump Europe still didn't manage to outpace economically the US by 2020, or 2024. In fact the gap has widened.