What nonsense. People explore, thats what we do. It doesn't mean the places that we come from are neccessarily bad (although that can be a motivation). Tenpenny's motivation for coming to America, and staying, are unknown.
http://www.1up.com/features/fallout-3-afterthoughts
"Allistair Tenpenny came to the Capital Wasteland from Great Britain to seek his fortune, so that alone tells you that the U.K. was also hit in the war. And if he came to U.S. to succeed, that says a lot about how screwed up Europe must be. So we just allude, a little bit, to the state of the rest of the world. We like to leave a lot to the players' imaginations, and somebody like Tenpenny serves as a catalyst for those thoughts.
—Emil Pagliarulo"
his motivations are well known, learn your facts.