No one wants to admit it, but Americans love being at war.
War gives people meaning - something worth dying for. It's 'exciting'. Even for those who aren't directly involved in the fighting. Parents brag about how their kids went to fight. Everyone makes heroes of them. And no one pays much attention to the reasons for the war, or how many people have been killed, and maimed, on both sides.
The fact is that a lot of people like war. On both sides, regardless of the reasons. The rich, who obviously like making money, will make lots more of it from a war. The poor, who's lives are already miserable, and who are looked down on, get jobs, and some respect, and a chance to see the world for joining in the fight. The middle classes, who are generally bored silly with their work-and-consume cycle of life, get a shot at some kind of "glory". And the politicians all get to show how tough they are, and how much they love their country without risking anything of themselves. And of course no one dares question them in wartime.
So everyone gets something they want from a war. And the few who know better had better not speak out. Or they'll be labeled an 'enemy' collaborator and treated accordingly. It's why warfare never ends. And it's why neither side is ever really "righteous", and why neither side ever really wins.