Do something, as in what? Take it upon ourselves to start a war and invade those countries? Try some “for good” assassination attempts?
Is it really the place of the USA to go to war against everyone it’s sure is evil in the world? Because we have an awfully poor record on that? Especially during the Cold War, we tended to be supporting and/or ignoring quite a large number of pretty obviously evil dictators and regimes “to fight communism”(tm).
Also, violent attacks on other nations don’t just do good, even when they succeed. They kill large numbers of people who are not part of the problem and create chaos and can lead to more wars, and are far more expensive than major social issues in the USA, etc, etc.
If you’re seeing pushback and disagreement about North Korea, I think it’s not that people disagree that the situation there is mostly horrible what with the death and suffering and so on, and that we’d love it to be fixed. The disagreement is, I think and hope, or at least in my case, that I think war is a major undertaking and could lead to more and worse wars and all sorts of other problems, and would not be guaranteed at all to end up being a net positive thing. Also I think there are major political things going on that are not about whether NK has an evil situation, but are more about trying to get people to think positively about war with NK, which I think has a less clear actual agenda behind it. It’s not good guy USA versus bad guy NK. More accurate is the anonymous entities which pull the strings and represent most of the wealth and power in the West find the chaotic nations who resist their financial manipulation to be undesirable, and so are using the news monopolies to try to eradicate the last remaining unowned loose cannon states, such as NK and Iran and apparently Syria (I don’t entirely get that scenario, or what’s really going on with Russia and China), and so we hear a lot of not entirely believable misinformation about all of them.