Trump doesn't approach things with a normal perspective. For Trump, it is all about appearances and how the Trump image waxes or wanes. A stable personality would first consider the loss of life a war would bring. A narcissistic personality first considers how he would look if he goes one way or the other. The loss of life remains an abstract as opposed to a reality. The personal image in history is more real to such a person. The way they look in the press is paramount. The loss of life is a statistic.
Trump doesn't want to listen! Trump wants to embrace military power like imbibing a drug as opposed to his actually exercising it in a shooting war. Trump wants a sure win not protracted struggle. What he really wants is to threaten and to then have them surrender or back off. He wants to feel the control of being able to order up a war rather than actually starting one.
However a necessary a war - a war that appears necessary anyway - would serve almost as well as making threats and having them take effect. A major war like WWII doesn't fit Trump's mentality. A big war with Russia or China is not the way Trump thinks. A smaller war where the enemy is not nearly so equal but could put up a credible fight is just perfect. Trump would willingly delegate authority rather than micromanage. He wants the credit of a win, so whatever they need, he is behind them.
Would Trump listen? I doubt he even realizes that there are other voices with other points of view that are talking to him. He is listening to his own narration of the Trump legend. Any South Koreans opposed to war - he doesn't really hear them because the sound of his own voice is too loud in his ears.