A world of free movement will not have a single welfare state.

Even after decades, and generations, immigrants from certain regions have absolutely abysmal rates of employment in more developed countries they have settled in. How would an even larger scale of immigration flip the trend we can already witness, a complete 180 degrees? Many seem completely content on living on benefits alone, or fully unable to find employment with the skill set they have gathered, even when they have born in the country where the natives fare much better. The way I see it, the money that is being spent on these people could be spent with a far better interest elsewhere.

78 trillion, truly, is a fantasy pulled from a behind.