After reading some posts I realized that Michael has transformed from a good citizen to a cold-blooded criminal due to fate at the end of the film. The movie seems to suggest he wanted to be a good citizen and not a criminal. He says at one point during the scenes following Vito that he has his own plans, apparently apart from joining the Army.
But as shown at the end of the film, even before the beginning of Michael's criminal life he did not join his father's birthday celebration even though everybody asked him to. This was after a small altercation with Sonny. It seems that Michael's personality was always cold-blooded. Both Michael and Fredo always secretly longed to be Don and waited for the right opportunity. In the meantime, Michael pretended to be a good man and Fredo pretended to be dumb. Michael realized that Fredo is happy for him not for choosing clean life but to lose a competitor during the birthday preparation. Michael reminds himself at end of the film that he had realized long ago during the birthday preparation that he will have to kill Fredo someday, as both cherish the same dream.
My question is whether or not the last scene can be interpreted to show that Michael always secretly wanted to be what he became at the end.