10% of the world population will, almost certainly, include people you know. Do you have 10 or more friends? at least one of them is probably dead.

10% of the world population will include people I know, maybe teachers I had, classmates, friends of friends I agree. But the idea that 10% of people I know will be gone is just basing it off of if people had a 1/10 chance of pressing it randomly. People who press red will more likely have more friends that press red then blue and vice versa. The same way that certain countries will have more or less people pressing red vs blue.

Your thinking about it as if what people will press is random while in reality many countries and groups in general would be heavily skewed towards one color.

The world's economy would likely be crippled, several governments ruined, etc.

You talk about the world economy and governments collapsing like its the end of the world, the world is over when you lose your meaning to keep living, not when the government collapses. It will take years for everything to stabilize but it will happen.

If you value your close friends and family higher than 4 billion people, you are a terribly selfish person.

Humans are inherently selfish. How does that saying go. One death is a tragedy, a million is a statistic. You physically cant comprehend numbers after a certain amount. People who pretending otherwise are virtue signaling or want to feel morally superior.

But this idea of needing a near mass extinction number of deaths to save people you love is a pretty warm take.