MacNamara and Johnson were evil without any mitigation. America's greatests enemies of their generation. That Johnson was elected to office proves the bankruptcy of American "democracy".
There are some who learn from their experiences, defeats, and disappointments, even when it turns out what they know is true just ain't so. Not Johnson and MacNamara!! We call this ability Johnson and MacNamara lack "intelligence". Patton and MacArthur had it, but Eisenhower was comparatively a dunderhead. As MacArthur described him, "the best clerk I ever had."
I could go on and lecture boringly on human nature, and loose my audience completely, because I rarely learn from my foolishness very well, and continue to act as if I knew what I was doing when I on some level know I don't!! Human nature, amazing indeed!!!
Like the Bourbons, they forgot nothing and learned nothing.