Elon Musk overpaid for Twitter when he bought it for $44 billion in late 2022, after unsuccessfully trying to renegotiate or renege. Now a new conventional wisdom is emerging: Twitter is a loss leader for the rest of Elon Inc.

Social media companies that once at least tried to promote a healthy information ecosystem have largely given up—and insiders say Musk’s example gave them cover.

Since the election, Mr. Musk has used his social media company to talk up how bright the future will be under the president-elect.