The spin-off game Fractured Daydream has a villain turn into Aincrad's floor 100 final boss exclaiming how much higher his stat has become.
Except the world they're in is influenced by people's will.
He was practically immortal before because that was his 'reputation' and the more he win the more he solidified that reputation.
But a final boss of a game? It's clearly made to be beatable.
So Kirito and co did just that.
Chat, when is it time to have a breakdown and start whining and crying and have a philosophical discussion? Of course, it's when you're about to get murked. Right in front of the enemy. He'll even wait patiently.