I really don't think you fully appreciate just how unaware this type of person really is to how they ACTUALLY come off to others.But there is a difference between getting told something and actually thinking about it when writing. Even if you write a self insert. And even if you are fully convinced you are the greatest guy ever. The disconnect to yourself just has let to some selfreflect. Unless you are a talentless scribbler who has no idea about anything. But we know that this is not the case.
I find it completely believable for one to write a self insert that's a smug, self-serving know-it-all who just effortlessly gets succeeds in everything because they're just that smart, and anyone who gets upset just doesn't understand, and they only really make mistakes because of totally unpredictable third party factors.
And I can see them doing it completely unironically with no self reflection, because of course she'll always be vindicated in the end, as they think they are in real life.