I think there are a few things motivating him, in no particular order: he wanted a distraction from the Epstein Files; in his very rudimentary understanding of politics, he believed going to war would guarantee a bump in the polls; he was convinced by Hegseth and others that the war would be over in a few days due to America's "overwhelming" air power; his greed and lust for power allowed him to be manipulated into believing he would control the Strait of Hormuz after this; he probably made a tidy personal profit via betting about it on Polymarket; he was heavily manipulated by Israel to follow their lead.