A holiday that lets us become someone else for a few hours seems like an obviously popular concept. Who wouldn't want to be Batman or Hillary Clinton for the night?
A holiday popularized by ghouls, ghosts, witches, goblins and other evil-doers is a less likely success. In real life, most of us don't want to be haunted, taunted, or scared.
So how does Halloween find the right mix of fun and fear? Candy. Whether young or old, candy is sweetness - both literally and symbolically. Candy puts us at ease and solidifies Halloween as a lighthearted event. Symbols such as candy are very powerful - that's one of the reasons why sweets are a part of nearly every popular holiday.