I didn't get the idea of why did Starlight become evil. I mean, Moondancer might be evil too, but she didn't. Twilight didn't come to her party and left Canterlot without even saying goodbye. And instead of being evil like Starlight, Moondancer became like Twilight was at first. She always read books and never hung out with her friends. So why did Starlight become evil? Her story is almost the same as Moondancer's.
Here is my question and come up with the answer that makes sense!