[dschiptsov]

Consider the magnitude change his character had undergo after he left mom's basement in New York.

Kerouac himself was smart-enough to realize the dynamic and illusory nature of what we call "myself" (it was one of his main themes - unfolding of Cody and himself and of everything else) and that his alcoholism was the cause of his suffering.

Why he didn't choose to fight it is another question. Perhaps, it was too late.