How come people worldwide celebrates halloween??

I asked this question in my self because, if you asked 10 people out there if they are afraid of ghost or any "not like ours creature", surely they will reply YES, so why celebrate Halloween?? For me celebrating Halloween is tolerating evil spirits, and making fun of them. And I think imitating their looks is not fun. And as I can notice many establishments are displaying different types of creepy creature but why? They are just spending money on that. So overall I can say that Halloween is just a waste of time, money, and effort. And Halloween is not fun at all. :'(

Wahaha...