Leaving one's place is one thing and going back to it or making a second big move another thing.
A lot of expats are where they are not so much because they choose to but because it was the only possible/reasonable choice at the time. Most of the time it was a non-choice.
When you start having a stable situation with adult level relations to your environment, like it or not chances are that it's going to take a huge amount on energy to change that. And any rational being knows that spending that much energy to "move on" is most of the time just not worth it and will lead to even more frustrations.
Migrants (a less prestigious kind of expats) experience that every day. Besides, it is funny that the term "expat" in French is used for people who are _sure_ that they won't stay in the visiting countries, mostly because they are sent there by their company for short to middle term high profile contracts.
People not of this sort like (or not) to call themselves expats because it gives them a sense of ephemerality that they can't even dream to experience. Most of the time they will _never_ go back home except for a few weeks to show the new born baby...
Migrants don't have many options at all, even high profile migrants. And their "bitching", if properly conducted, and sometimes mere presence on foreign land can actually offer locals who never moved out of their localism a whole set of new perspectives (and the inspiration to go check for themselves if the grass is really that green on the other side of the fence).
Migrants are the key to the fall of nations and nationalism.
Jean-Christophe Helary