At the end of the day, Diana loves being fawned over. She loves having these two men on a leash. She couldn’t believe Kael could possibly fall in love with someone else. Yes, we all know Hestia is steering this revenge, but she doesn’t. She’s blinded by hatred and jealousy. She blames Hes for Heli’s behavior, but she well knows that her “foresight” is about huge dangerous events and she’s been right, including Diana losing her powers.
She was going to bankrupt an empire simply to get back at Hes. She wasn’t going to invest because she’s so pure and frugal, but that went right out the window as soon as she heard Hestia’s name. What a piece of work this woman is.
whether Diana had genuine good intentions in the beginning or not, in order to keep a title like 'saintess' you can't be so easily swayed by jealousy or backbiting.. like it took Hestia almost nothing to turn her into what she has become now