Because our current society isn't a survival game where we fight over insufficient food. Mostly. Society ensures that most people don't have to choose between behaving nicely towards their fellow humans and feeding their family.

It seems a lot of the bunkerbros don't realize this value of society. They don't need society any more, they think.

> Why don't the cops and soldiers in our world do the same?

Consequences from the aforementioned functioning society that would have collapsed in the billionaire's dystopian survival fantasy.

Also, soldiers running amok in rhe absence of a strong government happens in our world - ask any civilian who's been caught up in an insurgency, or look at places like the Democratic Republic of Congo where armed militias run fiefs, and you have to pay tribute to operate a cobalt or lithium mine "their" area.