Some of our common 'demons' are:

You can befriend your demons, by facing them and objectively understanding the insecurity.

Our inner demons lead us to negatively judge ourselves, further leading to avoiding that judgment, and eventually starting the internal self-destruction, if the negative downward spiral is left unchecked.

Our inner Demons, or inner voices, make us do irrational, stupid and selfish things, based out of fear.

Carl Jung defined shadow as all of the parts of ourselves that we despise or loathe and therefore hide and avoid. It is impossible to run away or lose your shadow because ultimately, your shadow is a representation of you. 

Having demons or internal insecurities is not something exclusive, but is, in fact, a common reality among human beings.