Violence has always been part of human behaviour. There is some evidence that we are making progress. Also, despite the impressions conveyed by media reports, figures show that wars at least, wars between states, are getting less frequent and destructive in recent times. Maybe the UN should take more interest in resolving separatist conflict.
Nevertheless, we have a way to go. Humans have symptoms: War, crime, violence, hatred, rape, greed, theft, anger, prejudice, unkindness, coldness, psychopathy, disputations, thoughtlessness and arguments, you name it, we show it at some time or other.
The infinite diversity of vices can all be traced back to one single vice: selfishness.
Prioritising our own individual interests above the interests of other people.
In the case of the psychopath, the individual is absolute. In some cases, the "Family" (or in-group) is treated well, but those outside the Family are not respected. The Family may be the biological nuclear or extended family, or a social family, as in groups like Mafia or Cosa Nostra, or to sect members in the case of closed religious sects or cults.
This problem of selfishness can be viewed as a developmental problem. The human infant lives in a bubble of self-absorption. When a baby has needs - hunger, thirst, cold, etc, it yells, and the need (usually) gets attended to. Growing up is a process of learning that the needs of the individual must be balanced with the needs of other individuals. This is the process of socialisation, of learning that one is a member of a society.
If this process is radically disordered, we end up with a psychopath (aka sociopath) who cares only about his/her own needs, and is blind to the needs of others.
All this is pretty obvious. Why spend time setting it out?
Because the dominant ideology of our time is individualism. It is the ideology behind free market capitalism and libertarianism, and these are the dominating themes that drive climate change
We must always remember that individualism is also unscientific, since homo "Sapiens" is a social animal.
This is not to claim that all capitalists are sociopaths (though some are) The point of all this is, that for humanity to function optimally, we need to see beyond our immediate individual needs, and take a broader and longer view of the situation of all humanity, and of the environment that keeps humanity alive. We need to be able to see that others have the same emotions and needs as ourselves. We need to take a social and an ecological view of the world.
The point is that a world view based on individualism is unlikely to build the best of all possible worlds, because the narrow, individual world view is so often the problem, not the solution.