In December 2020, in the relative lull between Donald Trump’s defeat and Jan. 6, 2021, a right-leaning biotech entrepreneur named Vivek Ramaswamy joined a call with two billionaire titans of the right’s battles over speech and technology: Peter Thiel and Elon Musk. The subject was a plan to roll up a new tech giant that would be wide open to the speech, from extreme partisanship to vaccine skepticism, that had been pushed off platforms like Facebook and Twitter. The company would build a new...