Migration is a drop in the ocean when it comes to the problems affecting the welfare state.
We've been over this many times and the data you produce are always absurdly contentious. But don't worry: I will review a couple of the "money quotes" from that shithouse article you linked to make my argument.
Sweden has the most welcoming asylum policies and most generous welfare programs in the European Union. One typical refugee, Natanael Haile, barely escaped drowning in the Mediterranean in 2013. But the folks back home in Eritrea don’t want to know about the perils of his journey. As he told The New York Times, they want to know about “his secondhand car, the government allowances he receives and his plans to find work as a welder once he finishes a two year language course.” As a registered refugee, he receives a monthly living allowance of more than $700 (U.S.).
Why are we concerned about this? What, exactly, is supposed to be wrong with aspiring to work as a welder, and receiving what is actually a very modest living allowance in a country such as Sweden? Are we supposed to imagine that Sweden needs no welders? If so, provide different apprenticeships. Are we supposed to think that migrant language courses are a bad idea—if so, how can we complain about a failure to integrate? Are we supposed to think that $700 a month is a vast living allowance in Sweden? That's modest indeed. Are we supposed to think it should be taken away? How, then can we make arguments amount social dislocation and crime?
The article goes on to observe that Sweden has rapidly growing economic inequality without making any effort to determine its antecedents. Where is the evidence that migration is the root cause of this growth in economic inequality, which by the way is affecting every developed nation? As the article points out, Sweden accepts lots of refugees—so why then is inequality still rising consistently in all the countries that don't?
For a developed nation, Sweden continues to have a world leading degree of income equality, despite accepting all those terrible refugees.
Meanwhile, we have widely accepted economic analysis that has conclusively argued, from real data, that inequality grows because existing wealth enjoys greater economic returns than labour. You'll notice that in that sentence, the word 'migration' does not appear.
The article notes that statistically, it's harder to make a living as an African or Middle Eastern migrant in Sweden—well in the USA, black and Hispanic citizens also earn about 35% less than whites on average—is that because they are migrants or refugees? No. It's because white racism is utterly ubiquitous.
When ethnic disadvantage crosses generations in Sweden, and there is rapidly growing support for the crypto-fascist Sweden Democrats, one might speculate that a similar structural disadvantage is in play. If so, then it would be grotesque to blame migrants, particularly those who have arrived in flight, for the disadvantage inflicted upon them.
Sweden’s generosity costs a fortune, at a time when economic growth is stagnant. The country now spends about $4-billion a year on settling new refugees – up from $1-billion a few years ago, Mr. Sanandaji said. And they keep coming. Sweden automatically accepts unaccompanied minors. “We used to take in 500 unaccompanied minors a year,” he said. “This year we are expecting 12,000.”
The costs cited here of settling the numbers of refugees Sweden takes in is an order of magnitude less per capita than it would cost to intern them in overseas camps, as the EU's xenophobes are now beginning to propose more loudly.
The $4bn amount Sweden spends on their total refugee population of 90,000 is less than Australia spends per annum on border control and the detention of less than 5000 people per annum.
Remember that economically, the choice is not between accepting refugees, and accepting no refugees—it is between accepting refugees, and the state taking its own wildly expensive punitive measures, or funding those of other regimes to avoid a basic humanitarian obligation.