You ask why, even with the Bible in hand, I still make wrong decisions. The answer is The Bible does not make perfect; it is a guide, a light for our path. But I remain a fallible human being, prone to error and self-will. Knowing what is right and doing what is right are two different things. No man knows how bad he is till he has tried very hard to be good. The struggle is not the Bible’s failure, but a reflection of my own condition.
As for why it is so important to have the Bible and read and listen to it, I would say this: The Bible is not merely a book of rules or advice, but the record of God’s dealings with humanity. the story that makes sense of all other stories. As Christian it is the light by which we see everything else. The Scriptures do not close the mind; they open it to the presence and wonder of God and offer enduring wisdom for life’s questions. It bring us to Christ Himself. The Bible shapes our understanding, forms our character, and equips us for every good work. I return to it daily, not because I am flawless, but because I am in need of guidance, forgiveness, and the hope it continually offers.