Shortly after moving to Manhattan in the noughties I was strolling through the West Village when I came across a sumptuously upholstered sofa half-blocking the sidewalk. It wasn’t stained or damaged, so it seemed to me the most likely explanation for its presence on that manicured kerb was that, having paid a lot of money for it, its hedge-fund managing owner had decided it didn’t quite match the decor of his or her immaculately restored brownstone, and had simply donated it to the street, knowing that someone less fortunate would be grateful to find it there.