Unless we're going to say the war with Russia is fought with the same objectives (in this case have a US friendly government in power) I don't think we can compare against past wars.
That’s probably grossly inaccurate. Vietnam despite having a much smaller economy at time were still a major regional economic power even after consideration for internal conflict. Vietnam spent tremendous resources on the war. You also have to consider that the US participation in Vietnam was seen by the Vietnamese as foreign participants in a larger civil war. That conflict didn’t end just because Americans left, but rather when the communists took Saigon.