A) are happy to put up with what is a luxurious salary for back home, but barely liveable locally
Or B) don't have a choice once they're in, since they practically become indentured servants
In the Netherlands, no dutchie wants to work construction for example, because immigrants from Eastern Europe often take under-the-table deals where they get paid drastically less than what a Dutchie would command, though still much higher than any job they'd get back home. The same happens everywhere.
The answer is NOT to bring the country down by mass-importing low skilled workers, but by forcing these hugely profitable companies to actually invest in the country and its citizens by paying all employees as it should.