As an individual Halloween could easily pass by without my doing anything (Actually that's a lie, I like a scary book this time of year.)
But my children look forward to trick and treating so I would stick a few things on the front downstairs windows and get pumpkins a few days before (the number the few is depends on how the 31st falls in with the school holiday). On the day I put the outside things up.
My children are older now, and the youngest losing interest in it, so not sure how this year will pan out. Might do nothing.
I've a neighbor who has had stuff up since the beginning of October. They do every year, near the 31st they go all out. It's quite impressive!!! (They are the same for Christmas.) Rest of the neigbours are on the day for few days before.
To not 'know it is a thing' you'd want to every October to have never gone out the house (or walk around not noticing other people's houses), not watch TV or have been on MN before.
Otherwise it just seems like an odd statement. Almost like you want to show how superior you are to people because you don't do Halloween. Which is odd because it's not an achievement, it's a choice.
Especially enjoying those who claim they don't decorate only put a pumpkin or two out. So in fact do decorate!!