Here's why:
* Rarity is subjective: Rarity is influenced by factors like print run, condition, and surviving copies. Some comics with extremely limited print runs might be even rarer than Action Comics #1.
* Condition matters: A pristine copy of Action Comics #1 in "mint" condition is extremely valuable, but a damaged or poorly preserved copy is less so.
* Other rare comics exist: There are other comics with equally small print runs and high demand, making them potentially as rare as Action Comics #1. For instance, some early Marvel comics or specific issues with unique storylines might be considered rarer depending on factors like condition and market value.
Ultimately, the "rarest" comic in the world is a matter of debate and depends on how rarity is defined. However, Action Comics #1 remains one of the most sought-after and valuable comics due to its historical significance and iconic status.