Beauty contest's difficulty is overrated(this is gonna be a lot of yapping)
The manga and the show try to make it looks some smart math game but it really isn't. (This is about a game with an avarage player not kuzuryu or chishiya)
unless you assume everyone is gonna go logically, which (two of the first dying people did) you are gonna loose immediately the ammount of decrease the avarsge will have (if it even has) depends too much on the strangers youre playing with and let's be realistic most of the avarage payers aren't gonna overthink it.
Personall yeven if my life was on the line i wouldn't always pick the best choice because it would make the next avarages a lot easier to guess which makes it dangerous and more likely too lose especially when 4/3 people are left because of the ties and -2s.
when there's one person left if you have higher than -9 which is very likely unless you're playing against kuzuryu or smt you can win by choosing 4 yes ik very weird but it wins with 100 2 and ties with 1 and 0 (unless im forgetting something) so if you have a slight advantage or even a disadvantage you can win my contantly choosing 4 at last turn with maybe switching to 3 sometimes.
Some of the stuff might be wrong but i won 6/12 games i played on roblox so im an expert at this/j jokes aside roblox one did really make me see how much easier it was than it looked it's not exactly like the show it has -2 rule at start everytime so the games end faster but it still does tell a lot about the avarage player's thinking habits.