Why the men on the earth found causes to hate each other to build walls across cities and to kill?

The roots of hatred among men often stem from fear, misunderstanding, and competition for resources. Historical grievances, cultural differences, and the desire for power can exacerbate these feelings, leading to division and conflict. Additionally, societal narratives and Propaganda can perpetuate stereotypes and foster an "us versus them" mentality. Ultimately, these factors contribute to the construction of metaphorical and literal walls that separate communities and fuel violence.