There are many reasons to visit another place. But I think the most obvious reason is to learn more about different places and people. Why should someone restrict themselves to only knowing about their own home and people, when the world is so big. There are so many rich cultures, traditions, histories, travelling opens you up to all of it. This is especially true if you come from a country that is relatively young, like the US. American history other than for that of the Native Americans can be measured in centuries, where as in places like India, China or Egypt you can measured in much vaster quantities of time. Should we not then find out about the cradle of civilisation? Should we not find out what makes modern man, modern man? This is the reason why people travel, or that's what I think anyway.