I think a lot of it has to do with expectations. If you expect to be living a champagne lifestyle as an expat (and the days of country club membership, maids and chauffeurs are pretty much long gone), you'll probably be disappointed.
On the other hand, if you expect it will be a tough slog with lots of homesickness, it probably will be.
I have a lot of friends who have moved abroad but still call the UK "home", visit the UK for 9 weeks in the summer and 4 at Easter, still buy furnishings here that "will look nice at home" (i.e. the UK where their house and car is waiting for them) and whose kids still call the UK home, talk about their house and toys that they've left at home and how much they miss them. Imho they won't settle.
I think that if you go abroad with an open mind, determined to make the best of the situation and accept your new home, warts and all, you will settle. I know a psychologist specializing in expat issues who tells me that the parents who are positive about a move are the ones whose kids settle the best.
I've moved lots and left my country aged 21, still abroad 17 years later, lived in the weirdest and most wonderful countries, some 3rd world, some 1st world, but looked on each as an adventure and loved every minute.