Why would she be mad about the staff tho? It was the highest spec item for her class at the time; she has mad money, saw the price and agreed to it, then the staff was given to her. He may have priced it high but she got what she wanted as a buyer. Seyoung also gave all that money back to Heejae anyway; so in the end no one was really scammed.
(but yeah, she's def not mad about the staff; she's 100% being petty bc Heejae chose a guy over her, when she wanted to use him for self-promotion).
everyone mad at yoona but if that happened to me i’d crash out and go crazy too