How is it possible that so many idiots are considered "experts" - especially on national security matters?

Speaking of Jimmy Carter, his onetime national security adviser, Zbigniew Brzezinski, showed up for a talk at Duke University earlier his week, and the Herald-Sun of Durham, N.C., reports Brzezinski made this jaw-dropping assertion:

Brzezinski said there's no reason to think a bloodbath would necessarily follow a U.S. withdrawal [from Iraq].

"We expected that the U.S. leaving Vietnam would result in massive killings and genocide and so forth, and collapse of the dominoes in Southeast Asia," he said. "It didn't happen. How certain are we of the horror scenarios that have been mentioned in what will take place in Iraq?"

"It didn't happen"? Even the Herald-Sun is constrained to note: "History does record that a bloodbath that claimed millions of lives occurred in neighboring Cambodia, the so-called 'killing fields,' and that millions more people left Vietnam as refugees after the two countries fell in 1975."