TikTok arrived in the US advertising market with a product nobody else had , a feed so precisely tuned to individual interest that users describe it as reading their minds. That product advantage translated into engagement metrics that made legacy platforms nervous and advertisers curious. What it has not yet translated into, at the scale its audience size would suggest, is advertising revenue that matches the duopoly. That gap is the central tension in TikTok’s US business. TikTok has approximately 150 million monthly active users in the United States, representing substantial but not overwhelming scale compared to Facebook and Instagram,…