why do people wear a cross necklace?

I am so not religious but my guess is that the cross is a symbol of the sacrifices he made so it’s a reminder that one should live life to the fullest and not take it for granted.

Why not?

Because it's a necklace and necklaces are made to be worn?

Maybe they're a fan of intersections 🤷

It is a little odd if you think about it:

Maybe it's to ward off vampires just in case their day gets really weird.