Because they're not earning sixteen billion dollars for themselves, they "earn" it for the state by doing work that the people they work for them use to profit from. They're not the ones that get the money, it's their employers that do, as well as all the money they pump into the system via sales tax.
If Americans had those jobs at a living wage, chances are that would go down considerably. I'm not against that, but the employers and businesses sure as hell are. Assuming they can find Americans who will 'stoop' to such work in the first place.
And no, you didn't say those things, but you insinuated that they're siphoning money and not contributing.