Recently, I posted the summary of a shiur on Gneivas Da'as.
Perhaps the most common and pernicious form of Gneivas Da'as is people who are גונב דעת עצמם. The lack of self awareness many people have is FRIGHTENING.
People know far more about what is going on in Russia or China than what is going on in their psyche and in the psyches of those closest and most important to them. We all tell ourselves stories about ourlselves and many people's stories are just pure fiction. My *favorite* is when I hear people complaining about a certain negative behavior or trait of others when they theemselves EXEMPLIFY that very same behavior or trait.
If you want to be great - get to know yourself.
Well.