Where does arrogance come from?

Imam As-Sadiq (a.s.) said:
“ما مِنْ رَجُل تَجَبَّرَ أَوْ تَكَبَّرَ إلاّ لِذِلَّة يَجِدُها فِى نَفْسِهِ”

Translation
No one boasts to others unless he harbors a feeling of inferiority in himself!1

Brief Description
Recent psychological and psychoanalytic research has proved that arrogance and boasting is nothing more than an inferiority complex. Those who suffer from it resort to the practice of magnifying themselves artificially to compensate for their deficiencies. By doing so, they only add to their inferiority and dislike in the eyes of their community.
So clearly evident is this from the Imam’s saying. The faithful people are always modest before others due to their internal dignity.[divider]
•    1. Bihar al-Anwar, volume 73, page 225