The biggest thing in this book to me is that Job's fear is suggested to be the cause of his misfortune. Loss came because he believed that he would lose what he had. This is where his faith was placed, and he bets all his mental chips on it. This is the important part which kind of explains why the whole story happened, imo:
Job 1:5 ...Job sent and sanctified them, and rose up early in the morning, and offered burnt offerings according to the number of them all: for Job said, It may be that my sons have sinned, and cursed God in their hearts. Thus did Job continually.
Job 3:25 For the thing which I greatly feared is come upon me, and that which I was afraid of is come unto me.
26 I was not in safety, neither had I rest, neither was I quiet; yet trouble came.
He is continually fearing misfortune. So it comes. I really think satan in this story is Job's fear and Job's attachment towards life he has and fear of things not going well (in short, flesh mind that we all struggle with). I think that because of this fear, God tempts Job. The fear shows God, who sees into everyone's thoughts, Job's attachments and carnal - not necessarily always evil, but yes carnal - desires for things to go a certain way, which may come into collision and opposition with God's plans. So God breaks all things down at some point, to get through to Job. God gives rain to both the good and the evil and bears all things, good or bad. He wants us to be more on that wavelength and not focused on worries about benefits or misfortune. "But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you."