They really aren't. They do okay at it, but mostly they pay third-parties and use classification to maintain the (very important, from their perspective) illusion that they are master manipulators. They're mostly a bunch of over-educated Ivies graduates playing James Bond. They aren't as incompetent as they were in the fifties, but a big part of that is that they've figured out how to distribute their operations so that they have disclaimability on their side. That, plus the power of the spy mystique is the real secret of their operations.