To take this phenomenon further down the Rabbit Hole, if you pay close enough attention, a defined sense of self is just a feeling or thought that rises from time to time. However addiction/compulsion to perpetual thinking (which 99.99% of humans are caught in) plus the smoothing programs that provide a sense of continuousness and continuity begin to act on that sense of self firmly establishing a deep continuous sense of me. And there is a tremendous amount of conscious energy wrapped up in the perpetuation of a continuous sense of me. Certain states and activities more deeply lock the sense of me in including anger, conflict, proving yourself right, proving someone wrong.

Meditation and Hallucinogens can quiet the mind (or more dramatically short circuit habitual mind loops) and allow you to see the gaps in the self-ing process. The self-ing process never really stops. You never really stop having a sense of self arise from time to time, but when you see the frames and gaps of self-ing you begin to question a lot of who you think you are. And you begin to see the amount of time and energy you spend protecting the self from paper tigers.

Spiritual circles generally call this awakening and tend to over-emphasize it's specialness and idealize those who have deeply conditioned themselves to reside in that state. But it is real and mostly desirable phenominon (with a few drawbacks). Putting aside questions of full enlightenment and mind blowing transcendent unitive states, simply freeing up the consciousness that gets locked up in perpetuating the continuous sense of self and all the efforts to defend as if you are defending your physical body from harm allows for a richer, higher resolution and more textured moment to moment experience of life.

From my subjective experience it is the same sorts of filters that smooth out reality, that also give you a continuous sense of a psychological self which basically manufactures the vast majority of our problems and suffering.