GG is a classic narcissist.
"characterized by a lack of empathy, a willingness to exploit others, and an inflated sense of self-importance."
Flattery towards people who admire and affirm them (narcissistic supply)
Detesting those who do not admire them (narcissistic abuse)
Using other people without considering the cost of doing so
Pretending to be more important than they really are
Bragging (subtly but persistently) and exaggerating their achievements
Claiming to be an "expert" at many things
i've known a few. there is no reasoning with this type of person. They aren't really human, your only recourse is getting as far away as possible.