At one time, I had a lot of respect for Gen. Powell, given his Vietnam service and the First Iraq War, which was masterful. He came out thereafter with the Powell Doctrine, which was really a brilliant set of ten points to be referenced and satisfied before starting a new war. He had publicly disparaged GW Bush for what he was, a draft dodger, then oddly embraced him and became his Secretary of State. What then got me was that he discarded the Powell Doctrine entirely to go along with the Second Iraq War, made a fool of himself at the UN promoting it, and stood behind Bush instead of resigning. He then turned his back on the Republicans with his support of Obama, Hillary and Biden. So, his life was a very mixed bag - really impressive early on and then he seemed to do his best to destroy that reputation starting some twenty years ago.
His life and public career gives some insight to the forces that can tug at people, and how a person reacts can reveal their personal priorities. It appears that Powell was willing to change his core beliefs when he become a well-known public figure.
So he was a self serving opportunist?