If people could understand this and have a better sense about the scale of millions and billions, a lot of social problems plaguing humanity would be gone.

Which social problems? I think many people do understand this and problems directly resulting from a lack of this understanding aren't actually that present in the real world, but by the same reasoning, people think others don't because that's the poison you see on the Internet.

In day to day life, it's fairly acceptable to just acknowledge that some contingent of whichever population is made up of lunatics and move on with your life. It's only other lunatics, typically also only on social media, that can't do that, but normal people just don't bother paying attention to them. and hope they burn out.

I'm American and I grew up with many perfectly nice people (including family) that have held morally repugnant beliefs. Same for people in many other countries. Only exception are cab drivers - they get talkative quickly with no filter. I think the US is veering in the direction. People are complex. It's only when you get to know them beyond superficial conversations / introductions that this becomes apparent.

I don't know, I've seen Americans stereotype people up and down, but the moment you mention an American stereotype, it's always "this is a big country, there are lots of people here". Just notice how "Chinese people" and "IP theft" go hand in hand here.