It's useful to remember that Americans are a minority on the English-speaking internet. There's only 330 million of us, while the world has an estimated 1.5 billion English speakers. Probably much more if we include people that just know some of the language.
English is the global trade language, it's frequently taken in school as a second language all over the world. If you learn some English, the amount of activities available to you dramatically increases.
Sure, I'm not American myself. But I'm pretty sure much of the violent rhetoric on social media right now around killing CEOs etc is from Americans. The murder of Brian Thompson happened in America after all and all the anger around health insurance wouldn't really make sense in most of the world where there's universal health care.
Certainly. But anti-elitist sentiment is broader than just this country, as is anti-capitalist sentiment. There's a broad coalition of people that would celebrate something like this for a variety of reasons. I try to avoid taking people online purely at face value, since its so easy and commonplace to simply spin one's opinions slightly into something that seems similar to solidarity with one specific position, but in reality is operating from a subtly different motive in an enemy-of-my-enemy sort of way.
That said, I do agree that a lot of it is from Americans. But it would be in the interest of a variety of different chaos-interested positions to amplify that in any way possible. To a communist, its class warfare. To a geopolitical rival, it's a blow against stability. To the far right, it's a blow against the liberal order. To social media companies its an enticing engagement. Etc etc etc.