Why does performance drop when I increase ad spend?

Things work at low spend but efficiency collapses when I scale.

S: At 38%, the blended qualified visit rate clears the internal 30% benchmark. C: Traffic Intent Segmentation splits each session by the number of ICP criteria it satisfies — industry fit, company size, and behavioral intent keyword. I: At a blended CAC of $1,800, an ICP-fit visitor converts to a closed account with a 14-month payback period.