Because war is the health of the state. Looking at the historic evidence the cold war has changed the thinking of conservatives. Those who believe in a strong national defense are now believing that any conflict anywhere in the world is a threat to our national defense and accept whatever plans the government has as long as it's packaged right. Those who once feared world government and the UN now accept world government as long as the US is in charge. Conservatives accept corporate welfare, corporate/government partnerships, larger, more intrusive government and higher taxes when national defense is floated as an excuse.
Socialism is an unworkable economic system as it an unnatural state of affairs. It is doomed to failure. The communist countries were doomed to collapse but guess what? we have adapted socialism here in the US - the days of socialism are numbered here too. The old right and the libertarians were correct. We should have put our efforts into rolling back the New Deal when it was still possible back in the 40s and early 50s. The coopting of the conservative movement by the establishment has led us to socialism, empire and war. The defeat of limited government and sound economics was a major but unmarked mile stone. Future historians will find it interesting when they analysis our demise. Like all empires and like all socialists we can not escape the laws of nature.
The world is a better place because this war was fought and because we won it. To argue that it was all a mistake because it "saddled us with socialism" is ridiculous -- the fight against socialism continues. We haven't won it yet and we won't stop until we do win it.
If you choose to throw America on the scrap-heap of history, go ahead -- I don't care what you believe. I'll just point out that in doing so, you're in distinguished company. I seem to recall a fat Ukranian peasant, 50 years ago or so, saying something about a burial. He was right -- he just got the roles reversed.