There are 200 countries and the US is one relatively small, isolated pocket making terrible decisions and hurting themselves. Many countries hurt themselves and the US is just one of them.

US problems benefit their rivals immensely and is influencing their allies to become more independent and form new local alliances, there’s no benefit to anyone to long jump into one isolated hornet’s nest.

Sanctions are specifically difficult against the US because 1) they’re largely hurting themselves, most countries don’t agree the US is doing the wrong thing about Palestine/ foreign/other policy to warrant sanctions and 2) the US has so much, albeit dwindling, legacy political and financial/banking influence that sanctions won’t make much of an impact.

If your dog starts defecating on the floor and rolling around in it, you clean up your dog.

If your neighbor starts defecating on their floor and rolling around in it, well…

dog if you think the US is “relatively small”

look at what Nazi Germany, an even “smaller” country did – it started a world war and nearly took over an entire continent.

the fascist US, with a much larger influence, is an existential threat to the world.

The US is an existential threat to Canada and countries in the Americas that MAGA has bones to pick with. Maybe also Iran. The vast majority of the world is mostly safe, because America has no interest and/or capability to start shit there. For your Germany example, Hitler made it clear exactly what he wanted to do in Mein Kampf.

To us Europeans, the US also feels like a threat because it means an ally less against Russia.

You’re extremely naïve if you think the rest of the world is safe.

So the US is a threat because... it might not help Europe? That's not really how the word "threat" works, setting aside how Russia isn't even a military threat to non-Ukraine Europe in the first place assuming the EU's mutual defense mechanism holds.