Infrastructure was mostly built in Eisenhower's era, not FDR's. Helping Soviets during WWII was a major mistake and it can be personally attributed to FDR - a radical leftist - himself. Many people around him advised him of the dangers of helping Commies.
U.S. should have ignored Soviet-German war. Then finish Commies with nukes.
If they'd done that they'd be down in history as worse than the worst of communism. It was bad enough that they dropped 2 on the Japanese which scores American civilisation a questionable footnote in the history books. "Only people to use a weapon this terrible".
The problem with unprincipled aggression is that, sooner or later, other people match it. The US ended up doing much better by defeating the communists without directly fighting them - one of the few wars the US unambiguously won and why people don't want to learn that lesson is one of the great mysteries. Victories through overwhelming prosperity are both decisive and comfortable.
But that is the point! Get rid of everyone who wasn't friendly/under control, who could match it. Thus achieving worldwide democracy for all nations who could support it immediately, and unlimited time to get everyone who can't, prepared (with potentially unlimited violence applied to force them to). Achieve a sustainable hegemony.
U.S. should have ignored Soviet-German war. Then finish Commies with nukes.