It's Christmas Eve Eve!

It's time for a relax before the real festivities begin tomorrow and my usual Christmas Eve bake off.
Being in a long term relationship for three years meant splitting Christmas between Yorkshire and Lancashire. And now that I live with my boyfriend it is no different, so christmas day will be spent with the mother-in-law whilst boxing day will be spent with my mother, brother and sister in law in Blackpool.
Every year I provide the Desert for the Boxing Day extravaganza, and this year is no different - I will be making a child (and nut allergy) friendly Christmas cake (sponge) and mince pies a la Kirsty and Phil. So tomorrow will mainly be spent baking away for the most part of the day.
Today I bought my ingredients and braved the biggest Tesco in Bradford for 12 eggs, Filo Pastry, Cranberries, Clementines, Bramley Apples, Butter, Icing sugar, Jam, Mincemeat, Self Raising Flour and the last 2 Bags of Sugar in the whole shop.
My fiance assured me that the shopping expedition would go without a hitch, however, I always get a little anxious at this time of year. What is it about the supermarkets being shut for 1 day that makes everyone think a nuclear war is about to happen - they stock up on loaves of bread and bottles of milk like the end of the world is about to happen! I swear, the man behind me at the checkout had 8 2ltr bottles of milk and 4 loaves of bread - i'm surprised he didn't make it a nice round number and go back for 2 more bottles to make it up to 10!
Why do people do that?
Answers on a postcard...