People are forgetting that he said she could pay him what she wanted after seeing it. Her know-it-all behaviour is gross, and i agree it is distateful she didnt pay him anything, but he did give her a choice.
What I'm rolling my eyes at is the fact she got upset to that point...even when she knows she is meeting him earlier than she did in her last life. By a few years. Very foolish.
@mapokl part of that embodies the self-entitlement some people have when they become 'customers'. Yes, he could have asked what she wanted (and i agree that was missing from him here), but she could have easily also initiated such a conversation by asking what kind of paintings he does, what style, or tell him outright what she wanted - even if she thought she already knew (and this goes back to what i previously mentioned about her foolishness in expecting him and his work to be the same as what she saw before). So it was all set up for disappointment.
I'd like to think the author is trying to show that our protagonist is still immature and a bit blinded by her revenge, and not that her tantrum will be what saves this man and gets him on her side (like an author who wants their character to be a badass omniscient omg-she-solves-everything power 🙄).
Edit:
@Zephyr247 this, exactly. She knew that he became famous for a painting 3 years later, but expects his mastery and work to be the same before that painting is completed.
Even if this is all an act of her oh-so-calculative self to get his attention, i'll just be over here rolling my eyes.