Peace corps people often go abroad for the same reasons we do, to travel and meet new people as well as gaining new experiences. They do it on the government's dime though, not their own. That is often the only difference I see.

I have yet to find a Peace Corps member who proudly talked about going to some village with a mere 30,000 residents or so. Many of them often do without running water. There is no internet of course. Sometimes, you might find locals living in caves even. Going to the toilet means pulling down your pants next to a large pit. Teaching students who uses bricks as school desks along with a tent for a ceiling. These makeshift "schools" do exist in the poorer parts of China. Many places in the Northwest and along the Sichuan/Tibet border have these communities as well. I could not bring myself to teach in that type of environment for a mere 2,000rmb per month paid to me by the peace corps. I am sure that most expats would not do such a thing either.