The only way to see the illusory nature of the self is to look into the subconscious. The egoic self is mostly subconscious, which is why it’s hard to see. If it was conscious, it would have been easy to see.

All spiritual practices are designed to take you there, either by quieting the mind, meditating on something, chanting mantras, entering a trance state, or taking psychedelic substances. All of these methods just reveal the contents of the subconscious to consciousness, they bubble it up to the surface. The mistake most people do is taking one of such experiences as enlightenment and “truth”.

The truth lies beyond the experience. Any magical or transcendental experience you may have while using these methods is nothing but the contents of your subconscious bubbling up. The less stuff is there, the closer is the point of self-realization. At some point the illusory nature of the concept of self is seen, once and forever, and starting this moment, the process continues on its own - that is, there are no methods necessary, it becomes irreversible. Enlightenment is basically when nothing is subconscious anymore - there is no more subconscious to plunge into, nothing to bubble up. By that point, dreaming ceases, psychedelics don’t work, meditation becomes impossible and the concept of enlightenment itself is seen as illusory and empty.