In July of 2022, a woman we’ll call F. logged onto Instagram and posted a selfie from the hospital. “Just been told I’m on life support for my blood pressure,” she wrote, tagging the post with various medical terms and conditions: #gastroparesis, #addisonsdisease, #pancreatitis, #fullbowelobstruction, and even #lifesupport. Three days later, she said she was out of the I.C.U. but still struggling. By September, she was dead. A scroll through...