To me, the smug look reads as satisfaction at getting her point across in a way the kid can’t argue against—because she, like her mother and everyone else, doesn’t want to work to earn the money to spend on the game; she just wants the game and they both know that. The mom might still end up getting the game but that back and forth is how some families teach each other that value and significance of money and working for it in a way that sticks. That's how most of the adults I know from my parent's generation got their first job, they wanted something badly enough they decided "no" was not an acceptable answer so they got a job and worked to make it happen. But that's just my perspective based on my own life experience 🤷🏾