For many people it brings up memories of past holidays that remind them of emotional pain. Perhaps they have lost loved ones that are no longer here and they are constantly reminded that this is a time of year to be with those you love. Ouch.
Maybe they always have dreamed of having the perfect holiday celebration where everyone got along and all the hurts of the past are forgotten. Only to discover that the perfect holiday celebration is a big disappointment.
As children there was such a build up to the anticipation of the one day of Christmas and how much of that continues to be what we carry inside. And each year it is yet another disappointment, to the point that we would really prefer to not have the holidays at all.