Maybe true for common law, but definitely not everywhere. For example in Polish penal code: "Art. 162. §1. Anyone who does not provide assistance to a person in a situation threatening a direct danger of loss of life or serious damage to health, when he could provide it without exposing himself or another person to the danger of loss of life or serious damage to health, shall be subject to a penalty of imprisonment for up to 3 years."

It's obvious that this isn't universally true from a legal perspective, and certainly not universal from a personal perspective.

Now, you, personally - if you were watching a toddler obviously drown in a fountain, would you walk away?

That's monster-ish.

This is actually known as the Drowning Child problem, and its most important implication is that any billionaire is "extremely evil."

The parent comment would still be correct though, and billionaires are just filling a power vacuum, nothing wrong about that. I genuinely believe U.S. is also just filling the power vacuum & mostly has done nothing wrong, similar to other superpowers. There's nothing inherently wrong about letting the child drown unless you are the child & can protest about your own drowning, and there's nothing wrong with filling the power vacuum, because the universe has determined that someone ought to do it sooner or later. And we cannot do anything about this.

I define problem/issue/similar words in the following way: a thing that, if deemed existent by me, is also my own fault & realistically fixable by my self.