Crazy thing is that Peyton wanted to play another year... No one wanted him.
He was a pro's pro who changed the game of football at the line of scrimmage. Truly changed the way offense was ran to a certain extent.
To finish his career, John Elway did more for this guy than he could ever repay. When Elway saw his skills diminishing last year he went out and created an absolutely dominant defense. That defense was so good that they were able to overcome the shittiest QB play in the league for much of the year. Peyton gets to retire a champion despite playing absolutely terrible football all year.