From China (with an estimated population of 1,335,830,000 people) to the estimated population of 50 people for Pitcalm Islands, 223 or more countries are currently existing in the world. That leads to a rough figure of 6.8billion people of the world today, who are living their lives, fixed in one place or the other, or are fortunate to have the opportunity to live and travel from place to place, from time to time.
Whether it is for work or for personal reasons, people travel or go on vacation because they are in search of something that can't be found from where they came from. Being away for how long, depends on how difficult and how much of that something is needed, before the traveller's return journey takes place.
Most important are those souvenirs on the return trip that accompany the traveller. Unless the souvenirs are suffice to represent the reason for the trip in the beginning, then there's no telling when and if the traveller will ever free-willingly decide to return. If the traveller does return despite of it, it will just be a matter of time before the traveller decides to take-off again. Again it will be in search of that same something that's missing, only this time the traveller may still or may not be going at it alone.