The NSA sells the job to naive college students on patriotism and generic descriptions of working with cutting edge cool stuff. Once you're in, it's easy to rationalize that all this will be used only for good. Especially if the alternative is quitting your stable job that supports your family.
Many of the low-level analysts are very smart enlisted personnel with ranks of (E1 to E5) from among the various services. Many of them use the GI Bill to pay for college. Some stay in the IC, while others move one to different careers.
