I think some people, maybe no kids of their own so they have a little money, remember what a big thrill it was for them as a child, and they just really enjoy being A Generous God one night a year. Seeing the faces light up. Maybe especially if they're estranged from family so no gifts to buy. I live in a condo and the few kids in the building go elsewhere to trick-or-treat, so most people don't do anything, but my neighbor down the hall puts out a bowl of regular -size (not giant but not mini) candy bars October 1st and keeps it filled the whole month! I just put out a bowl of little ones on the night.