It seems awfully cynical to think there's no tech work that you would take on to justify a little cut in pay. If it's not for you, it's not for you. But there are huge swaths of people who get real satisfaction from working on the problems that government work exposes them to.
It has little to do with patriotism nor the monetary value of your work. People do things for incentives – they can be monetary or otherwise. As someone else mentioned, federal employee benefits can be really, really fantastic for the way some people want to live their lives. Probably not for those wanting to own a Maserati by their 30th birthday, but for those who want a low-risk, comfortable retirement after a consistent (if lengthy) tenure it's not a bad option.
I can name at least one "huge corporation" (in Silicon Valley, no less) that very successfully offers lower salary compensation for a shot at similarly meaningful work. Maybe these arguments never hold up because it's hard to be "patriotic" about the 38th x for y startup to launch this week.