I posted an opinion that the reason we continued to discuss Lost online twofold: to keep Lost alive, and to dispute the garbage that was abundant out there on the Internet. I have the definitive answer to the smoke monster's existence and realized that I had posted it everywhere BUT on my fave site.
The smoke monster is probably almost as old as the Island. I say almost because Jack was able to kill Flock who was the corporeal embodiment of the smoke monster when he unplugged the Island's power thereby taking away MIB's immortality and his own partial immortality. However, the smoke monster was extant on the Island as early as 5000 years ago when the Island was in proximity to Egypt, as indicated by the hieroglyphics showing the smoke monster amid the Egyptian symbols, and the presence of the statue of the fertility goddess whose name escapes me. Since the Island can travel, and the Egyptians were not known as a maritime civilization, the Island must, at that time been located somewhere in the Mediterranean Sea.
Which brings us to Mother, 3000 years later and a continuity error on the part of our beloved writers. Although in Across the Sea there is no mention of the smoke monster not being a part of the Island, in fact it is implied that he is indeed there and the Island needs to be protected from Something, wires got crossed somewhere and some of us ( just a few) were left with the impression that the smoke monster was born when MIB was tossed into the light and Smokie came roaring out. This was not true. Smokie was angry that anyone had entered into the light. Remember, Mother had warned both Jacob and MIB not to enter the cave of light or something terrible would happen. Could it be that the smoke monster was the guardian of the cave up to that point? Was the smoke monster the protector of the Island? It would be logical for such a powerful creature to guard such a treasure. In mythology there is always a monstrous creature who guards the treasures. Mother was certainly aware of the smoke monster, she had lived on the Island for thousands of years and was tired, waiting for her successor who could co-exist with the protector. And when necessary she could take on the guise of the smoke monster to do damage such as destroying the village and covering the well when her son got too close to being able to leave the Island.
There was no reason for the smoke monster to want to leave the Island. It had been there forever. It knew no other existence. When MIB met his mother's spirit, he was cursed with the desire to leave the Island. His was the worst possible body for the smoke monster to invade. If the smoke monster's purpose was to protect the Island, now his purpose was to leave it. His nature and purpose had changed.
Whereas before his sole purpose was to keep a watchful eye on anyone who came to the Island and make sure that the secrets were kept secret, now he wanted to figure out a way to leave. The existence of the donkey wheel and his knowledge of the electromagnetic properties of the Island would serve him well.
When the Others came, and the Dharma scientists, and the Oceanic 815 survivors, Smokie used them to further his plans. His was a tragic existence. We know only of his "life" after 2004 and various flashbacks and flashforwards. And of course the cryptic conversations between MIB and Jacob. If only MIB had never met his mother;s shade. How different the story of Lost might have been.