Musar על ברכות 109:1

What I have explained so far may also help to answer a very serious question concerning Joseph's conduct when he interpreted Pharaoh's dream. Having explained the meaning of the dream, Joseph next volunteered a piece of advice to Pharaoh (41,33) which he introduced with the words: ועתה ירא פרעה איש נבון וחכם, "Now let Pharaoh appoint a wise and understanding man, etc." What business did Joseph – a slave and a prisoner to boot – have to offer gratuitous advice to Pharaoh? Clearly Joseph had aspirations to attain a position of authority in order to be able to further Divine plans and to replace the position of the שרו של מצרים, the regular spiritual patron of Egypt.