>>19526813>>19526427He explained it to Cody in a seliloqui. He was facing the fear of being forgotten, and that had taken hold of him. Curiously, that is the greatest fear of the Orphan (shadow of the Hero) archetype, which is abandonment. The Orphan is born when the Hero begs the world that he saves to do something for him for a change. John Cena embraced the shadow, became selfish.
This entire arc is about Cena coming to terms with his own end. And in the end, the Orphan heel who promissed to ruin wrestling so he'd forever be remembered decide to go out humbly, tapping out to promote the next generation that will take over this business as act of atonement to the business. And as an act of atonement with himself, by the hero archetype, Super Cena accepts its own end and taps out on camera, effectively giving its farewell to a decades-old bond with fans and going out with a smile, letting John Cena finally be free.
John Cena returns as a man who does not have to be Super Cena to know that he is deserving of love. Because when he taps out, the fans understand that it was not because he gave up, but because he earned it.