What’s your source on this? When humans have no obligations they usually turn around to be super nice to each other. Humans are social animals and they really really want everyone they know to do well.
Are the people in the current US administration, or the tech leadership, or the people in power in Israel or Russia looking particular nice to you or interested in the wellbeing of all humans?
Were the European colonialists nice to the people in Africa or South America or the settlers in North America to the natives?
People are super nice - to their own ingroup. The relationship to everyone else is less friendly, especially if power differences are involved.
„Common wisdom“ dictates that humans are wild animals, and the only thing keeping us from tearing ourselves apart is a thin layer of civilization. This is sometimes called the „veneer theory“.
That theory is wrong.
It’s also very important to powerful people that you believe that the theory is right; because why else would you allow eg. an autocracy to exist?
So, to answer your questions:
> Were the European colonialists nice to the people in Africa or South America or the settlers in North America to the natives?
No, but the natives were nice to the settlers.
The reason we have some nice things in the modern world, flawed though it is, is because for the last few centuries the military-industrial meta has favored countries which let people have some political and economic freedom. In a previous era, the meta was knights and peasants; a country without knights would be conquered, a country without peasants would starve, and a country that did not give the knights power over the peasants would lose a civil war. It doesn't matter what people want; technology will diffuse, someone will play the game to win, and any countries that choose less optimal choices will just be swept away.
in any case, how is one country/power with winning on their mind getting infinite manufacturing and raw resources to construct this robot army?