Nell Diamond, the Yale M.B.A. and daughter of former Barclay’s C.E.O. Bob Diamond, made one of the more fortuitous pivots in recent fashion business history when she redirected her somnolent D.T.C. bedding brand, Hill House Home, in service of its one great creation, a blockbuster product that defined the pandemic era and now comprises more than 20 percent of the company’s revenue: the Nap Dress. Indeed, the dress transformed the business. It helped Hill House Home generate more revenue in a single day in 2021 than in all of 2019. The following year, the company raised a Series B at a $150 million valuation. Hill House Home declined to comment on its financials, but people in the industry assume it makes more than $100 million.