Demand isn't the job. Order is.
At this scale, the risk was never an empty room. It's a chaotic on-sale: crashes, touts, furious fans, wasted press. The campaign's job is to move enormous audiences through announce, presale and general sale in clean waves, with the right fans reaching the front of each queue.
Email is the presale engine
Announce sends, presale access codes, reminders sequenced to the minute around each window. Segmentation does the heavy lifting: the diehards who bought the last three tours need different messages at different times to the maybes who streamed one album. Get that wrong and you burn goodwill at scale.
Paid covers the edges
Paid ads reach the fans the database doesn't hold, retarget the ones who visited ticket pages and stalled, and shift weight between cities as demand data shows where the pressure is. The discipline is exclusion: never paying to reach someone who already bought.
What smaller promoters can steal
The same structure scales down to a 400-cap room: build the list before the announce, give it first access, sequence reminders around real deadlines, and spend paid budget only on the gaps. A sell-out is rarely luck. It's usually sequencing.