This may be dangerously close to the realms of armchair psychoanalysis, but I have a feeling that Wu's egotism and eagerness to proclaim herself an expert in everything despite not having the prerequisites to back up such claims is because she views the world through the logic of the one thing she has actually put vast amounts of time into: video games.
You put in Call of Duty and you're immediately a highly-trained soldier with a vast knowledge of weaponry, play Bayonetta and you're a witch with cool powers, in Sim City you're a mayor, architect and town planner; you 'become' these things without any effort on your behalf. Most people understand this is just escapism, and that it's fun to play roles you wouldn't ever be able to in real life and that if you were to, would either require a lifetime of effort or be straight up impossible.
Brianna, of course, is different: she applies this video game logic to the real world. She wants to be a software engineer? She is one in her mind. She wants to be a expert mechanic/street racer? She is one. Congresswoman? Yeah that too.
To Brianna real life is the same as switching the disc that's in the Playstation.
