She really played them bad. She's not nice
She did say she was sorry in the end (while crying).
It's better to do a harsh training in a controlled environment with an instructor present.
A dungeon is a really harsh environment
Had to leave this comment thread for a while to let go of previous emotions.
I think if you would think like that in that environment and situation, that's cool. But, given that previous raids with Jieun ensure everyone is not only fed, but also are provided on-hand snacks and emergency provisions, I would be piss-poor made that the one who isn't training is pigging out off of someone else's abilities. It doesn't matter if the one training them is capable of solo the highest level of tower; that's just being no different from a corporate boss.
If I were them, I’d make Yura not eat for a day. Actually, why didn’t Jieun just recall the truck since that’s where all the grilling is? No food for anyone, and she could summon it again to crush her.