I do not get it.
This is a serious question:
What is happy about Halloween that deserves to be celebrated and to be wished to others?
Instead one might wish a scary, creepy, fearful, frightful, freaky, deadly or morbid Halloween.
I understand that people make a lot of money from it, but in essence it is a day with mainly occult and demonic roots: https://en.wikipedia.org/wiki/Halloween
The Christian feast of All Saints´ Eve may be seen different as it celebrates the deceased saints who died expecting and hoping for eternal life in Christ.
But Halloween? What´s its happy bit?
Kind regards
anaesdoc