Training oneself to become a hacker and then working for the NSA is like graduating law school with an emphasis in environmental law and then working for BP.
Except you hackers are already sellouts. Hackers complain that the United States does bad things in order to ensure a smooth oil supply, but then they fly or drive to Las Vegas for DefCon. In the hacker's mind, they are not to blame for burning oil, companies like BP are to blame for selling them the oil. While at DefCon, hackers consume vast amounts of electricity and water -- in the middle of a barren desert. Even the cheapest Vegas hotels are more luxurious than "nice" hotels in the third world. Hackers enjoy all the benefits of a peaceful, prosperous society created by our government and corporations, while complaining about how those benefits are obtained.
It's like that famous joke: A guy goes up to a beautiful woman in a bar. He asks her "Would you sleep with me for a million dollars?". She says yes, she would. He then asks "Will you sleep with me for $50?". She slaps his face, saying "What do you think I am?". He says "We already know what you are, we are just negotiating price".
We already know hackers are sellouts, it's just a matter of negotiating price, finding out what hackers are willing to sacrifice their principles for.
While selling out your principles on the small things, your don't understand the big things. The typical DefCon punk has a distorted view of the world that is one large conspiracy theory. But the world is not so black and white, but shades of gray. You'd see that with a few classes in economics or political science, or by reading books.
There are many good books. The latest one I read is The Interrogator, written by a CIA interrogator of "high value targets" that were subjects of "extraordinary rendition" to "black sites". The author, Glenn Carle, sharply criticizes the Bush administration and its abuse and torture of such prisoners. This sounds exactly like your little conspiracy theories, but it isn't. Instead, Carle is respectful of the CIA and clearly for the "Global War on Terror". The situation is not black and white, but shades of gray.
The Enemy of the State. The NSA (mostly) doesn't spy on Americans. It operates under strict control of the executive branch. Certainly, President Bush relaxed those controls a bit, allowing the NSA spying to leak over into our borders, which is probably unconstitutional, but it's not the evil conspiracy you imagine.
The fact of the matter is that you'll compromise your principles less biking to work at the NSA than you will driving to work (gasoline or electric) at any other job.
The biggest downside working for the NSA isn't being a sellout, but working for a bureaucracy. Yes, you'll get to work on exciting projects, but most of your efforts will be the mind numbingly dull tasks, such as filling out paperwork. Ironically, much of that paperwork will be dealing with the checks and balances to prevent you from hacking Americans.
More to the point, if you ever see something where the NSA truly is doing something unconstitutional, then you have the chance to do something about it. Quit your job and become a whistleblower. It would be sad indeed if the only people who worked for the NSA were those who were willing to sacrifice their principles and go along with any activity, no matter how illegal.
Reddit comments: http://www.reddit.com/r/netsec/comments/jyoia/hackers_working_for_the_government/