During World War II, scientists created a revolutionary super soldier formula to turn frail Steve Rogers into Captain America! Those scientists were killed by Nazis a couple minutes later, so they never got a chance to see if pumping experimental DNA-rewriting drugs into a boy too weak to pass an army physical had any massive psychological side effects. Man Comics proudly presents... Captain America: B.ipolar A.ntisocial D.isordered A.merican S.uper S.oldier.
This should have resulted in years of therapy.
Sometimes it's just a matter of making the US Department of Defense look, like, REALLY cool.
Actual impending doom like global climate change or mass extinction just makes people bored.