In December of 2012, three young men were living in a claustrophobic apartment in San Francisco’s Tenderloin district, working on a technology startup. They had received a hundred and seventy thousand dollars from the incubator Y Combinator, but their project—a plan to make inexpensive cell-phone towers—had failed. Down to their last seventy thousand dollars, they resolved to keep trying out new software ideas until they ran out of money. But how to make the funds last? Rent was a sunk cost. Since they were working frantically, they already had no social life. As they examined their budget, one big problem remained: food.