We like to think we can define our identities by our own efforts, that we can create ourselves from nought like the primal Greek gods who ruled before the Olympians.
Not only is this not true, but humans can only be defined in relation to others; our cosmogony necessarily always includes those we orbit and those who orbit us. Shifting orbits is possible, but it is not easy, and no one springs from the nether fully-formed, Khaos in robes of air and mist.
Identity is indeed not immutable, but the way we believe we can try on and slough off identities as easily as a model doffing and donning dresses in a changing room is not the way human psychology or culture works, or even can work. This is neoliberalism refracting through and corrupting the psyche, offering choice where there really is none, producing nothing but anomie and dread of the inevitable unmasking that reveals no face at all beneath.
Identity games are what we play when we’re convinced that the insubstantial and the irrelevant is paramount, while the great criminals are allowed to infringe against our civlization unrestrained.