why does Morocco change his mind and say that he deserves portal?

Morocco is reading the silver casket which reads, “Who chooseth me shall get as much as he deserves.” Morocco muses that he deserves a lot but perhaps not Portia. Then he thinks that he must not undermine himself or he will lose her. He decides he is worthy of Portia after all.

Morocco,after having doubts his worth to win Portia,later on changes his mind. He feels that he deserves Portia because of his royal birth,his wealth, his virtues and his upbringing .Above all ,he is worthy of her because of his deep affection for her. ..