Culture shock
This can be very real. Family or social difficulties at home and psychological problems, including alcoholism, make adapting difficult. Time differences between continents might increase isolation when it is difficult to maintain contact with friends and relatives. A situation that is exciting and welcome to one person can be daunting to another. Possible problems include adjusting to a different climate, unusual food, religious and cultural differences, separation from family, changes in living standards, different social amenities, language differences, coming to terms with poverty, begging, and compulsory movement restrictions for safety or political reasons.
Being open to new and different cultures and being patient, rather than critical, will help the traveller adapt to new and challenging adventures.