Sure, there is a sizable percentage of Americans who are filled with do-gooder "change the world" intentions. That's why we invented things like the Peace Corps, so we could get these pests out of our hair. The ones for whom this was only a youthful phase were supposed to come home sadder and wiser (and much thinner from weeks of dysentery or malaria), and settle down and get productive jobs. The ones that were hopeless (ie, too egotistical to admit their ideals were about as substantial as cotton candy) were supposed to stay in foreign places like Gambia or the UN building and thus out of our hair. Unfortunately, things went a little wrong. But there's always the possibility of other solar systems to figure out how to escape to explore, and it will probably be Americans who figure out how to do it, too. If we left one neighborhood gone bad, we can leave another.