Not a trope when its true and factual. Hell, ex-CIA directors have even admitted it in books and TV! Most Americans don't like hearing that their government can be one of the "bad guys".
This would be true if there wasn't a huge list of coup attempts in developing countries backed by the U.S. dating back almost a hundred years up until today. It's not a conspiracy, the U.S. has engaged and continues to engage in political interventions world over when they deem it necessary.
Lately? HN is a forum derived from an American company and promoting Silicon Valley culture. Most of the points of view of everything (not only politics) are strongly skewed towards American culture and beliefs. I would find it surprising if it was different .
There'd probably be a fairly strong seeding effect though.
And HN is anything but a random sample people from a given country; to be part of the tech scene you kinda have to take an interest in what is happening in the US and it certainly pays to be pro-SV since historically they provided a lot of well paid jobs. That'd be a huge bias in opinion.
I think it's usually a bad idea to attribute any broad sentiment to HN as a whole, but if you wanted to make the point that it's a tech industry forum and thus shares (with many counterexamples!) tech industry biases, that's a much more grounded thing to say than that it's a "Silicon Valley" site.
I will say this, though, and it's a wild guess so take it as you will: the median opinion among American tech industry workers about the government of Bolivia is: not, in any way at all, ever once thinking or caring about the government of Bolivia.