Here’s one reason Donald Trump seems perennially in a bad mood: he has probably figured out that the America he fantasizes about is out of his reach.

However many immigrants he manages to deport or prevent from entering the country, the white paradise he is promising his Maga base, free of Somalis, Mexican “rapists” and generally people from “shithole countries” – closer in hue to the America where he was born – is not his to offer.

He can, however, do a lot of damage. By doing his best to make the US unbearable both to foreigners and, more generally, people from ethnicities that do not mesh with his picture of the American family, Trump is not Making America Great Again. He is ensuring America will be smaller, older, weaker and easier to push around.

Nothing Trump does to stop immigration can change this trajectory. Because the non-Hispanic white population will keep on shrinking regardless, the Census Bureau projects that it will lose 3.6 million people over the next five years, almost 11 million in the decade after that and more than 14 million in the subsequent one.

And that means that if Trump and his ethnonationalist sidekick Stephen Miller achieve their goal of cutting future immigration down to nothing, the US population will shrink pretty sharply. It will be 6% smaller by mid-century, 10% smaller by 2060 and one-third smaller in 2100. The president may not fully realize this – his grasp of economics has proven tenuous – the demographic squeeze would come at a substantial cost.