RE: President Eisenhower warned us of the military industrial complex “deep state” in 1961. Promoting wars made them rich.
So, bottom line, in hindsight, should the USA have engaged in the Korean War or not?
Not. Same with Viet nam, Kuwait, Iraq and Afghanistan.
Counterfactual history speculation is always fun. What would Korea be like now if it was entirely overtaken taken over by the Kim regime? Would it be like Vietnam in the cold war - in the Russian camp? Would it have undergone any kind of reform by now?
Remember too that Korea, Vietnam, etc... were outside of Kennan's original "containment" proposal - they were considered poor, insignificant countries not worth fighting over.