[2022] HOW IS THAT EVEN POSSIBLE?

Yesterday (18th Jan) after creating a public Lobby, a player joined with a level of 103!!! On Playstation. And here I thought I grinded alot with my level 18, playing almost everyday... Given the release on 1st of Jan. Can someone do the Math how much this Person must have grinded total / played per day?! When we say average XP per mission is around 7000XP (maybe less given that some missions fail) and an average time for mission is 30min(?). Anyhow Rock&Stone to the Lad who can kill bugs all day. I envy you! I wish I had the time and the tenacity!