But this begs the actual question-what is the underlying belief that makes it so easy to take Americans to war again and again?
That would be the assumption that the US is the "policeman of the world", which is sometimes mentioned, but only in the "we should stop that" way, not in the "who died and left us king?" way. So those who are pro-war easily fall for the latest "Bad man has scary weapons, so we must bomb and kill the people of his country", and those who are anti-war tend to stick to "There is no proof that Bad man has scary weapons, so we should not bomb and kill the people of his country" arguments.
But there is no clause in the UN Charter that specifies the US as the enforcer of international law. There is no internationally agreed designation making the US the sheriff of the planet. This is simply a role that the US has usurped, using the power of its control of the media to convince the public that it is traditional and accepted. And ironically, the US unilaterally changed "international law" into "the rules-based order", with no international agreement, just slavish obedience from the media and the vassals. Who gave the US the power to do that? It is just assumed that the US is the boss of the world.
Until this assumption is challenged and overcome, the US will be able to continue its path of causing chaos and destruction in any place, at any time, around the world.