Answer:

Travelling can expand one's outlook, amplify one's experience and make many new friends. It could be a superb lesson in one's life. If I have/possess adequate time and money to plan my tour, i would prefer to tour foreign countries. Foreign life can serve various life experiences and lifestyles which are hardly acquired in domestic life. In the identical social and environmental circumstances, people generally have relatively familiar and similar views and experiences. The distinction is, if any, slight. If people do not go abroad, they can rarely obtain refreshing ideas. For example, some people who come from highly industrialized countries with high welfare, tend to take the free healthcare and education for granted, but if they have a foreign tour in impoverished countries or regions where the food is almost far from enough, not to mention schooling, they can be taught a precious lesson: Cherish one's own life and help someone who needs help.
Oversea travelling can offer broader choices. As far as I know, some countries are as small as one common city of the United States. In such countries, if people refuse to journey abroad then they have to repeat his footprints time and time again. On the other hand, some countries are located on some lonely islands without forests and all the fish comes from the sea, if these residents want to ride a horse in the plain or taste freshwater fish, they have to travel abroad.
Besides, the exotic landscapes and customs are more curious and attractive than familiar ones.
Generally speaking, people are curious, they prefer to acquire purely refreshing experiences, rather than relatively familiar or even well-known ones. The foreign lifestyle, food and scenery are always far different from one's own domestic experiences, which is the key factor IN satisfying people's curiosity more deeply.
In conclusion, foreign tour can afford more various life experiences, more options, and satisfy people's curiosity. These advantages appeal to us. Needless to say, these are the contributing factors that attract more and more people to travel abroad.