I agree with travelespresso being an answer of both. First, the obvious is can one afford outside of their own country? Next, in my view is the purpose. At the workplace of experience seems most traveled outside to foreign destinations (I live in San Diego area) were through cruises by both young and old. The points of destination for the ships was the means. Then it was to a major port and going beyond the port is limited to how long there and etc.
That does not answer the question. I think it definitely depends on purpose for importance and just where the beginning point is. Living in France a days' drive may offer of least two different countries - Germany and Spain. The same driving time for me to get to Oregon or New Mexico. Yet, both offer diversity while language differences may become the biggest hurdle for the earlier choice.
I would really like to go to Crete and Greece. I like studying Greek philosophy and love their epic poetry and mythology. I would love the ambiance of the land, the people, the plants, the waters, the foods, the culture, and the history of lands.
I have those same desires with U.S. interests such as the days of the 49'ers and the gold rush era. That is closer to home. Yet, oddly the desire to venture closer to home does not have the sense of intrigue masked by the known of the major cities and culture is not any different than in my own backyard. The desire is the history, the adventures, and the legends or lore of that era, yet easily that may be discovered reading. The mysticism seems not as attractive to venture, yet the result would be the same comparative with Greece and Crete.
Possibly one may revive interest in another with appreciation. I dun'no . . . since we are writers here most will see opportunity for either choice and opportunity for creating memories with imagery is immense. Yet, that is only one purpose for experiencing travel. I guess a quote by Mark Twain may sum it up . . . and he infers traveling abroad.
“Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome, charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime.”