"You can't sit with us" - The Persian Mean Girls

The reason why Persians didn't see Greece as "worth their time" was because of how prosperous the empire was on its own. Under Darius I the Persian empire became the largest empire the world had ever seen. By having such an extensive empire that encompassed various regions a mesh of different social and political groups as well as resources. Therefore, the Persian empire would have had contact with a vast array of people, cultures, and materials, creating a more diverse empire. Additionally, such a large empire was maintained through various organizational procedures. Such as well maintained and patrolled royal roads that connected regions to the center of the empire. This ensured that even far off sections of the empire would have to maintain contact with the central political powers. The Greeks being in such close proximity to such a powerful empire would obviously spread rumors in order to maintain their own high status and make people believe that they were far more sophisticated and dominant than the Persians. For instance the Greek stereotype of Persian queens make them out to be diabolical power grabbing women, when in fact Persian women often protected their family members and mediated conflicts. To me it seems like the Persians were just doing their thing and building an awesome empire and the Greeks took it personally.