Jeez, where to begin....
Currently there are 31 nations that do not have an actual organized military (all nations have law enforcement, no matter how small). The largest nation without an organized military is Costa Rica. They even have a "Army Abolition Day" every December 1st.. Having said that, of those 31 nations, none hold any strategic value or significant resources to benefit other nations, thus they are largely ignored.
But nations being in what could be considered by other nations as being in a "strategic" location, or having resources that competing nations vie for, find it necessary to have a military for their own safety. Then of course, there is always some individuals who can be charismatic, that have their eyes set on "ruling the world." The public, being gullible can and do, go along with their grandiose orations, as in the case of Hitler and Mussolini. The pacifist leaders ignore them at their own nations peril and then you have the "war" you don't want, as the goon and his/her army role across various nations. Britain's Prime Minister Chamberlain was convinced that Hitler was no threat and his government went along with his "peace" stance....and ended up fighting for their very lives because of his "pacifist" stance.
As we know, violence and war caused by religion has been responsible for killings over many years. Catholics against Protestants, Islam against every other religion. Territorial wars are also common. India and China and Vietnam and China, have military confrontations over territorial disputes.
The idea that the military-industrial complex is the main culprit in wars is naïve. The militaries are the world's governments method of responding to threats, disputes and defense. You will never see the world in one harmonious voice, singing kumbaya, as each seeks to benefit their own people and themselves over others.
If you will recall, President Biden, not so long ago, said publicly in a town hall meeting that the United States no longer needs a standing army. He knew when he was saying that, that he was B.S.'ing the public, he just wanted to pander to the crowd that wanted money from the military to go to social services.