Your mistake is in equating the US to other countries. You cannot. It is a superpower.
When other countries act hostile to the US, it can simply ignore their sovereignty at a whim, and this is a huge benefit to living in US.
Is it unfair? Sure. Who cares?
Obviously, there's more than just military might, we have the most innovative and powerful economy on the planet as well.
However, with a country like Venezuela, where none of our allies truly care what we do (sure, they might blow hot air but whatever), we are free to use hard power to achieve our objectives.
However, international law has always been a thin veneer over the reality of international relations. History shows that nations act in their own self-interest, regardless of the "rules."
The concept of one country "bullying" another is irrelevant moralizing. You are applying playground rules (or the rules of civil society) to a global stage defined by anarchy: there is no "teacher" to stop the "bullying" here. It is a zero-sum game of security and power. At this level, "bullying" isn't a meaningful concept, only leverage is.
Should the world be this way? I wish not. Political realism is a grim framework. Unfortunately, game theory tells us that so long as any one superpower believes in realism, the rest of us must as well, or risk getting outmaneuvered. And Russia/China certainly believe in it.
What do you mean, "who cares"? Obviously a lot of us not from the US care, and many Americans care, too.
Even if the answer to the first part can be narrowed down to a few nations, the answer to the second part can be narrowed down to zero.
What Trump just did is an act of war, undeclared and deceitful in every way.
It makes diplomacy much harder to do in the future. It makes the US untrustworthy.
That's explicitly been the case since 45 was elected a second time. Even if we get an adult in charge again, there is no guarantee of stability anymore with the way the population is.
