Self-aggrandizement, self-opinionatedness, gloat, and boast are techniques people deploy to (hopefully) cover up what they lack of.
These behaviors stem from the desire to keep up with others, to be perceived that you are better than others, even if it is just a tad better.
The inability to accept your own limitations and shortcomings makes it impossible for you to nurture your own talents. Because all your life is devoted to come out better than someone else you meet—someone else who has different talents than you do.