If you were to serve in an intelligence agency, you’d probably spend an overwhelming amount of your career looking at the world through a soda straw: you might know a heck of a lot about our cloak and dagger activities in Kenya, for example, and nothing about anything else. Presuming you’re good at your job, you may get promoted to cover all of Africa, and perhaps start working for someone like (or become) the Deputy Director for Operations for the CIA. So then you’d be at a point in which you probably know a little about everything. All it will take is 20 to 30 years excelling in a bureaucracy!
There’s other points of convergence: you could be the White House Chief of staff, on the staff of the NSC (last time I checked we’re talking about 80 or so staff), or a budget analyst for the Office of Management and Budget (someone has to account for the cost of electricity to keep Kennedy’s head in the cryogenic tank). I’m sure there are other positions I haven’t listed (CIA historian, for example) but you get the point.
Good luck. Hope you wouldn’t be disappointed if you work 30 years to achieve your goal only to find that Roswell was indeed a weather balloon.