what is an "expat"?
an immigrant? migrant? a special kind of immigrant? hm...
But nowadays, it's usually high income immigrant westerners who don't want to be considered 'immigrants' because that's for <whisper> poor people.
After I've dealt with the US immigration processes years ago, I just call everyone who lives in a different country an 'alien'. Fuck this doublespeak.
This article actually features the company which published the 'study': https://www.bbc.com/worklife/article/20170119-who-should-be-... See if you can ignore the neocolonial tone and figure out expat vs immigrant vs migrant.
Rich country to anywhere: "expat".
Historically, though, immigrants were permanent while expats were expected to go back at some point.
Or at least that's what matches the usage I've seen the best.
Expat = temporary
Immigrant = permanent
And sure, lower income foreign workers might have it worse than rich foreign workers, but they still come for the benefits.
No, I'm saying exactly the opposite. They aren't, they're non-immigrant temporary workers, thus technically 'expats'. However, they're more often referred to as 'migrant workers' and this report, for example, does not include them.
Another example is Mexico. There are a couple hundred thousand Americans living and working in Mexico. They're considered expats. But a Mexican temporary visa holder is considered either a migrant worker or a legal alien.
This report, however, does not appear to include them in their survey, suggesting a mismatch between your definition, and that used by an organization which claims to be "the largest global expat network" with "4.5 million members."
Indeed, you'll be hard pressed to find poor temporary workers from less developed described as "expats".
For example, I've noticed few people refer to the ~200K low-skilled temporary Mexican laborers in the US under the H-2A visa as "expats", even though they fit your definition.
I've further noticed that "illegal immigrant" is used even for people who intend only temporary residence in the destination country.
"American expatriates in London"
It had generally been used for retired people, but remote (pandemic) workers have greatly expanded the word's meaning and usage.