One of the refrains of Michelle Obama’s memoir Becoming (2018) – which charts the former first lady’s journey from her working-class origins on the South Side of Chicago to the White House, by way of Princeton, Harvard, a high-end corporate law firm (where she met Barack), and a series of executive jobs in the non-profit sector – are “four words that reliably plague even the most accomplished and powerful people I know”: Am I good enough?