Early last week, the top executives of Airbnb Inc. gathered in San Francisco for annual planning meetings. They were brimming with confidence. The home-rental company had exceeded financial projections for 2017, with $93 million in profit on $2.6 billion in revenue, said people with knowledge of the matter. Airbnb was ready, by some employees’ estimations, to begin the process to go public. But the boss had another view. Brian Chesky, the 36-year-old co-founder and chief executive officer, privately informed his financial chief, Laurence Tosi, that Airbnb wouldn’t initiate an initial public offering this year.