The goblin you killed will respawn in 30 seconds. The dragon you killed for those boots takes two days to respawn, and you killed it 32 times to get the boots; if you go back, it is still there, still giving out boots (rarely).
You beat the game and immediately start it over. It is a song that never ends, and you sang a verse once.
You log out of the game and never log back in. Maybe you said goodbye. Maybe some players remember you for a while. Maybe someone notices in the guild log that you have not logged in for 574 days and wonders whether to /gkick you. Maybe you will be back. The guild roster is gradually becoming a graveyard. Have we forgotten the players who left, or is it the ones left behind who are forgotten?
There are memories in your head and entries in a database somewhere. You were a great hero (+500 XP). You destroyed the enemy nexus (+2 ELO). You saved the kingdom (quest available again in 19:59:59… 19:59:58…).
Your parents tell you to be careful what you post online, because the internet is forever. Maybe some of your data is archived forever, but much of it is as lasting as a fallen leaf. It grew. It changed colors. It feel beautifully and perhaps unseen. In the spring it was dust, new mulch for new growth.