In 2009, Iron Maiden played in Chile at Club Hippico, - 65k people in attendance; they could easily do the same, even at the same outdoor venue.The problem (if there is one) could be the Santiago's location. Fans are disappointed in the adjacent park to the stadium, and in 2022 they've skipped Chile altogether just because the stadium wasn't available.
But it could also be that everything is going accordingly to plan. AC/DC shows are sold out, Guns is doing an insane amount of shows in Brazil only, and Maiden will most definitely outsell them anyway.
